Data from the

NATIONAL HEALTH SURVEY

Skinfold Thickness

of Youths12=17 Years

UnitedStates

Skinfold measurements at five anatomical sites are presented

and discussed by age, sex, race, and geographic region of the

country for youths 12-17 years of age in the United States,

1966-70.

DHEW Publication No. (HRA) 74-1614

U.S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE

Public Health Service

Series 11

Number 132

Health Resources Administration

National Center for Health Statistics

Rockville, Md. January 1974
Series 11 reports ~ :sent findings from the National Health Examination

Survey, which ol dins data through direct examination, tests, and measurements of samples of the U.S. population. Reports 1 through 38 relate

to the adult program, Cycle I of the Health Examination Survey. The

present report is one of a number of reports of findings from the children and youth programs, Cycles II and III of the Health Examination

Survey. These latter reports from Cycles 11and III are befng published

in Series 11 but are numbered consecutively beginning with 101. It is

hoped this will guide users to the data in which they are interested.

Vital and Heakh Statistics-Series 11-No. 132

For saleby the SuperintendentofDoorrnmnts,U.S. Qover’mnentPfitfrx Omce,Washington,D.C. ‘20402- price $1.0S
NATIONAL CENTER FOR HEALTH STATISTICS

EDWARD B. PERRIN, Ph.D., Director

PHILIP S, LAWRENCE, SC.D., Deputy Director

GAIL F. FISHER, Assistant Director for Health Statistics Development

WALT R. SIMMONS, M.A., Assistant Director for Research and Scientific Development

JAMES E. KELLY, D.D.S., Dental Advisor

EDWARD E. MINTY,, Executive Officer

ALICE HAYWOOD, Information Officer

DIVISION OF HEALTH EXAMINATION STATISTICS

ARTHUR J. McDOWELL, Director

GARRIE j, LOSEE, Deputy Director

PETER V. V. HAMILL, M.D., Medid Advisor, Children and Y6uth Progwns

HENRY W. MILLER,. Chiej Operations and Quality Control Branch

JEAN ROBERTS, Chief Medical Statistics Branch

SIDNEY AmAHml, chie~ Nuti’tion Statistics Branch

COOPERATION OF THE BUREAU OF THE CENSUS

In accordance with specifications established by the National

Health Survey, the Bureau of the Census, under a contractual

agreement, participated in the design and selection of the sample,

and carried out the first stage of the field interviewing and certain

parts of the statistical processing.

Vital and Health Statistics-Series 11 -No. 132

DHEW Publication No. (HRA) 74-1614

13braty of Congress Catabg Card Number 7$600228
CONTENTS

Page

Introduction -------- -------- -------------- ------- -------------- -------

Method --------------------------- ---------------------------- --------

Results --------------- -------------- -w----- ------- -------------- -----

Age Differences -------- ..,D---- --------------------- -------------- --

Sex Differences-- -------------- ------- ------- -------------- ------- -

Race Differences ---------------------------- -------------------- ----

Relationships to Data from Cycles I and H-------------------------- ---

Correlations Among Skinfolds -------- -------------- ------------------

Geographic Differences --------------------------- ------------------

Triceps Skinfold Thickness by Age and Weight -------------------------

Comparison With Other Studies --------------------------- ------------

Discussion --------- ------------------ --------------------------- -----

Age and Sex Differences ----- ”--------------------- ------------------

Race Differences ----------------------- -------- ------- ------- ------

Correlations Among Skinfolds ----------------------------------------

Summary ----- --------- --------------------------- --------------------

References -----------------------------------------------------------

List of Detailed Tables --------------------------- ----------------------

Appendix 1. Statistical Notes ---------------- -------- ------- ------- ----

The Survey Design -------- ------- --------------- ------- ------- ------

Some Notes on Response Rates --------------------------- ------------

Parameter and Variance Estimation ----------------------------------

Standards of Reliability and Precision ------- --------------------- ----

Hypothesis Testing -------- -“----- -------------- ---.--- -w----- ------

Analysis of Correlations Among Skinfolds ------- ------- ------- ------- -

Imputation ---------------------------------------------------------

1

2

3

3

6

7

8

9

10

10

10

12

12

14

15

16

17

18

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52

53

54

54

54

55

55
CONTENTS-COn.

Page

Appendix II. Demo~aphic Variables -----------------------------------

Age and Sex--------------------------------------------------------

Race --------------------------------------------------------------

Re@on ------------------------------------------------------------

Appendix III. Techniques ofMeasurement and Quality Control -------------

Inwoduction --------------------------------------------------------

HES Measuring Technique --------------- ------- ---” ----------- ----.-

Surveillance and Evaluation of Residual Measurement Process Error----

Monitoring Systems ----------------------------------------------

Biases and Controls in Replicate Measurements ---------------------

Selection of Replicate Examiners ----------------------------------

Evaluation of Residual Measurement Error in Skinfold Measurements----

Results of Replicate Examinations ------------------------------------

Inter-Examiner ~fferences ---------------------------------------

Intra-Examiner Differences -------- -------- -“------ -“----- ----------

Conclusions -------- ---------------------- --------------------- .-

SYMBOLS

Data not available ------------------------ ---

Category not applicable ------------------- . . .

Quantity zero ---------------------------- -

Quantity more thanO but less than O.05---- 0.0

Figure doesnot meet standardsof

reliabilityor precision ------------------

*

57

57

57

57

58

58

60

62

62

62

63

64

65

65

65

67
SKINFOLD THICKNESS OF YOUTHS

12-17 YEARS, UNITED STATES

Francis E. Johnston, Ph.D., Peter V. V. Harnill, M.D., M.P.H., and Stanley Lemeshow, M.S.P.H.a

INTRODUCTION

This report presents skinfold measurements

of youths 12-17 years of age in the noninstitutionalized population of the United States, as estimated

from the Health Examination Survey (HES) of

1966-70. Findings have been analyzed by age, sex,

race, and geographic region. Publication of this

report completes a series describing and analyzing the quantity and distribution of subcutaneous

fat in individuals and groups over the age range

of 6-79 years.

The HES was conducted as a series of separate programs, called cycles, each of which examined national probability samples of a specific

age range of the noninstitutionalized population of

the United States for a variety of information related to health and development.

Cycle I in 1959-62 focused on the prevalence

of certain chronic diseases and the distribution of

various physical and physiological measures

among the adult population, ages 18-79 years, as

described previously.1’2

During Cycle II in 1963-65, a range of factors were examined in children 6-11 years of age

including those related to health, growth, and

development.3

Cycle III, 1966-70, the program on which the

findings in this report are based, was further designed to obtain basic measures of growth and

%ofesmr of Anthropology, University of Pennsylvania,

phi]adclpMa; Medical Advisor, Children and Youth pr0gr~s2

Division of Health Examination Statistics; and forrnerly@dyticd Statistician, Division of Health Examination Statistics,

twpectively,

development, as well as data on other healthrelated characteristics of the adolescent population ages 12-17 years. The survey plan, sample

design, examination content, and operation of this

survey program have been described in a previous

report.4

Most of the results of these three cycles are

appearing in this series (Series 11) of the Viful

and HSUMZStatistics reports. Skinfold measurements from Cycle I (adults 18-79 years) were

published in Series 11, No. 35;5 those from Cycle

II (children 6-11 years) were published in Series

11, No. 120.6

For Cycle III, a national probability y sample

of 7,514 noninstitutionalized youths 12-17 years of

age in the United States was selected. Of this

sample, 90 percent were examined. This national

sample and the examined group constitute a

representative sample of the 22.7 million noninstitutionalized youths 12-17 years in the United

States with respect to age, sex, race, and geographic region.

From the standpoint of human growth and

development, the adolescent period is one of intense interest and extreme importance. It is &tring these years that the body structure of the child

is transformed into the morphology of the adult.

Apart front the secondary sex characteristics,

much of the sexual dimorphism observable in

adults arises during adolescence and virtually

the entire body in some way participates in the

phenomenon known as the adolescent spurt, characterized by marked changes in the growth rates

and by rapid movement to adulthood.7 For these

reasons the battery of measurements taken in

Cycle II was altered and expanded for Cycle III,

1
after considerable discussion and consultation, so

that the data obtained from Cycle III would reflect

the changes in size, shape, and body composition

associated with adolescence.

One of the most important features of human

development, and one receiving more and more

attention, is the composition of the body, i.e., the

constituents of its mass, and the changes of these

components. While there are many models used

to partition mass, from a quantitative aspect, into

its component tissues, depending upon the investigator’s instrumentation and the problem

under consideration, the measurements of the

thickness of skinfolds at specific and appropriate

sites provide an acceptably accurate and demonstrably meaningful parameter for estimating the

degree of fatness of the body. 6 In addition, it is

the only approach feasible for epidemiological

surveys involving large sample sizes. Finally, it

is basic to the evaluation of fatness/leanness in

the clinical examination of individual subjects.

The use of skinfolds and the integration of these

data with those obtained from more complex and

involved procedures have been covered in a number of publications, e.g., by Bro~ek8 and by

Malina.g

This report presents the distributions of

skinfold thicknesses among youths 12-17 years

old at five sites on the body, as measured in Cycle

III of the HES, and as related to age, sex, race,

and geographic region, along with certain analyses

of the differences noted. The format is similar to

the report on skinfolds from Cycle II 6 to allow

extrapolation and integration, and where appropriate, data from the 6 through 11-year-old sample are included to provide a more comprehensive

view of the growing years.

Statistical notes, including survey design,

response rates, and reliability of the data, are

included in appendix I. Appendix II lists pertinent

demographic variables, while appendix 111describes measurement techniques and quality control procedures.

METHOD

At each of 40 preselected locations throughout the United States the youths were brought to

centrally located mobile examination centers for

an examination which lasted about 3 hours. Ideally,

six youths were examined in the morning and six

in the afternoon.

When the children entered the examination

center, their oral temperatures were taken and a

cursory screening for acute illness was made;

if illness was detected, the youth was sent home

and examined later. The examinees changed

into shorts, cotton sweat socks, and a light

sleeveless topper, and proceeded to different

stages of the examination, each one following a

different route. There were six different stations

where examinations were conducted simultaneously and the stations were exchanged. At these

stations there were examinations by a pediatrician, a dentist, and a psychologist, and at the

others highly trained technicians performed a

number of other examinations, including X-rays

of chest and hand-wrist, hearing and vision tests,

respiratory function tests and electrocardiography, an exercise test (treadmill), a battery of

body measurements, and a grip strength test.

In Cycle I of the HES two skinfolds were

measured. One more was added for Cycle H. The

considerations mentioned in the hit roduct ion warranted another increase for the Cycle HI examination of youths and consequently two more were

added, bringing the total to five skinfoldso

All measurements were made on the right

side of the subject, if possible, and recorded to

the nearest half-millimeter (mm.). Measurements were taken twice, and, where necessary,

any discrepancies were resolved by means of a

third measurement. In all cases a Lange skinfold caliper was used; this instrument is designed

to exert a constant pressure of 10 grams/mm. 2

throughout the range of jaw openings. The precision of the caliper was tested daily by checking it against metal standards of known widths.

Periodic training sessions were conducted

by outside consultants to insure continued proficiency in the measurement techniques and to

obtain replicate data for the purpose of quantifying observer error. The results of the replicate examinations are presented in appendix HI

together with a description of the technique of

measuring skinfolds.

Each of the skinfolds measured was selected

either because data were available from Cycles

I and II and/or because each provided a significant piece of information on the dynamics of sub2
cutaneous fat deposition during adolescence. The

rationale for selection is described below. Diagrams of the five skinfold sites are shown in

figure 111in appendix III.

The triceps skinfold was measured over the

triceps muscle at the midpoint of the upper arm.

In addition to it being the site at which skinfold

measurements are most frequently taken, it

provides information on the quantity of extremity

fat and may be a valuable indicator of obesity.*O

The subsca@davskinfold was measured just

below the inferior angle of the right scapula. It is

the next most commonly measured skinfold and it

allows an estimate of fat on the trunk. Some

studies have suggested that it may be the skinfold which, by itself, is most highly correlated

with total body fat.11

The midaxillwy skinfold, taken in the midline as its name implies, and halfway between the

nipple and the umbilicus, provides another estimate of trunk fat at a site where the thickness of

the adipose layer is minimal.

The suprailiac skinfold was added in Cycle

III to permit an estimate of subcutaneous fat

deposition at what is perhaps the major “depot” of the body where quite marked amounts of

fat accumulate in some individuals. The skinfold

was picked up over the crest of the ilium inferior

to the midaxillary region and measured along a

natural line with a front-to-back axis.

The medial calf skinfold, also added in Cycle

III, was measured to provide information on lower

limb fat and to enable one to conclude whether

the triceps fold was in fact a valid indicator of

both the upper and lower extremities. In a few

individuals the skin and underlying tissues were

“stretched” so tightly that a satisfactory fold

could not be picked up at this site. No measurement was recorded for these subjects; however,

they amounted to only 1 percent of the total

sample measured.

In all of the reports from the HES, age is expressed as the years attained at the last birthday,

and the grouping for this report follows this convention. The mean age of each category, therefore, approximates the midpoint of the whole

year; e.g., the 13-year-old male group consists

of a 1-year cohort whose mean age is 13.49

years, while the corresponding female sample

averages 13.48 years. The ages were validated

from birth certificates in 92 percent of the subjects.

“Race” was recorded as “white,” “Negro,”

and “other races. ” The white youths made up

83.98 percent of the total, the Negro youths 15.71

percent, and youths of “other races” only 0.32

percent. Because so few youths were classified

as “other races, ” data from them were not analyzed separately. These data are included when

“total” is used but are dropped when a white/

Negro dichotomy is employed.

RESULTS

Age Differences

Tables 1-5 present the basic distributions of

the data by age and sex. All of the values were

derived from the weighted sample sizes. As discussed in the report of skinfolds from Cycle 11,6

the mean and its standard error are presented

mainly for the information of those investigators

who continue to use them. However, the marked

skewness of all distributions strongly argues for

the use of the median (50th percentile) as the best

measure of central tendency and for percentiles

as measures of variability. These parameters are

used in the analyses in this report; the means

are used only when special information can be

gained from them.

The percentiles are graphed by age and sex

for each skinfold in figures 1-5 to permit a visual

evaluation of age trends and sex differences.

The skewness described for the Cycle II

sample is also quite evident in these figures, the

distance from the 50th to the 95th percentile being

considerably greater than that from the 5th to the

50th, regardless of the age, sex, or site.

Among girls, there is a general tendency for

the medians to increase from one year to the next,

indicating a steady accumulation of fat throughout

adolescence. However, there are some exceptions

to this statement which warrant pointing out. The

median midaxillary fold increases through age 16,

but the value for 17-year-olds is less. At the

suprailiac site, the median skinfold thickness for

16- and for 17-year-olds is less than for the

preceding age groups. For the 17-year-old group,

the decrease is in the order of the increases noted

for earlier years and, in view of the design and

3
MALE

‘0 r

30

28

26

24

22

20

18

16

14

12

10

8

6

I

4tFEMALE Percentile

~::

:~ :~

12 13 14 15 16 17 18 12 13 14 15 16 17 18

AGE IN YEARS AGE IN YEARS

Figure L Distributions by selected percentiles of the triceps skinfold of U.S. youths, by age and sex.

32-

30

28

26

24

22

20 —

16

16

14

12

10

8 —

6

4

2

o_

FEMALE Percentile

+.

@h

y:

~’$

I I I I I I o~

12 13 14 15 16 17 18 12 13 14 15 18

AGE IN YEARS AGE IN YEARS

Figure 2. Distributions by selected percentiles of the subscapular skinfold of U.S. youths, by age and sex.

4
28 —

FEMALE

: : ~:;’

!: ; 2“”

y

: : ~’”’h

u.

z

:

g

;; : ~’”’h ;: : ~—’’”

~

g ‘;

10

5 ~ 75’

6 —

8 ~ ~::

~ %

6

4 —

~ ‘$ 4

~ ‘$

2 — 2

0 I I I I I J o I I I I I I

12 13 14 15 16 17 18 12 13 14 15 16 17 18

AGE IN YEARS AGE IN YEARS

Figure 3. Distributions by selected percentiles of midaxillary skinfold of U.S. youths, by age and sex.

FEMALE

: :2: !~-::

g; ~ ~’oth : ~ ~’”’h

y

24 — 24 —

g

22 —

z

g 20 —

u

18 —

: : ~ 75%’

<

~

g

:

: : ~75’h ; : ~_~m,h

12 —

‘; :~; ‘: ~ ~ Z’th

4—

~ 5t’ : - ~ ‘2[

2— 2—

0 I I I I I 1 0 I I I I I

12 13 14

I

16 16 17 18 12 13 14 15 16 17 18

AGE IN YEARS AGE IN YEARS

5
“ r

MALE FEMALE

Percmtllo

!5-f

c1

“l32t30t

2!-

o~

12 13 14 15 16 17 18

AGE IN YEARS

36

34

[

32 —

30

28

26

24

22 —

20 —

18 -

16

14 -

12 —

!0 —

8 –

8 -

4 -

2 —

@h

~th

o~

12 13 14 15 1-/ 18

AGE IN YEARS

Figure 5. Distributions by se)ected percentiles of medial calf skinfold of U.S. youths, by age and sex.

sample sizes of Cycle III, it is difficult to ascribe

it to sampling error.

For the triceps, medial calf, and subscapular skinfolds, the medians for girls show a consistent increase from 12 through 17 years.

On the other hand, the curves for boys show

basic differences among the five sites. The three

skinfolds which reflec~ trunk fat (subscapular,

midaxillary, and suprailiac) display the same

general pattern of increase as noted above for

girls, though the slopes of the lines joining the

medians are Iess, suggesting a sIower rate of

accumulation of fat in boys than in girls, In contrast with the pattern for girls, the median skinfolds for the triceps and medial calf generaIly decrease with age, indicating a relative loss of fat

in the arms and legs in boys during adolescence.

In terms of absolute values, the greatest

medians are to be found for the suprailiac and the

medial calf skinfolds. The percentile distributions

of these two overIap a great deal, and it is therefore difficult to make positive statements about

one of the two skinfolds having greater vaIues

than the other. However, with respect to the

medians, thicker skin folds are to be found at the

medial calf among girls. The same is true in

boys 12-14 years, but thereafter, as the medial

calf medians decrease, those for the suprailiac

fold become greater.

The skewness in skinfold distribution was

quantified by dividing the difference between the

95th and 50th percentiles by the difference between

the 50th and $th. b Thus a symmetrical distrilmtion would have a value of 1.00. Skewness values

are shown in table 6. In all cases the curves were

skewed to the right, as evidenced by values in

excess of 1.00 and they were frequently markedly

so, with values sometimes greater than 6.0.

Greater skewness was noted for trunk than for

limb fat.

Sex Differences

The differences in skinfold thicknesses between boys and girls are twofold. First, girls

b

This method was devised because of its simplicity, While

it is recognized that there are other measures, e.g., the con~putation of the third moment about the mean, they are much

more complex in their calculation and yield equivalent information.

6
may be observed, at any site and at any age, to

have greater median thicknesses than do boys.

At the subscapular and suprailiac sites, the differences between male and female medians show

no pattern of change; at the midaxillary site, the

differences become greater with age.

Boys and girls differ also in the curves of

sltinfold thickness and age for the triceps and

medial calf. While the medians increase with age

among girls, there is a persistent decrease in

boys from 12 through 17 years. This decrease

serves to accentuate the sexual dimorphism by 17

years. By that age the 50th percentile values for

girls are more than two times those for boys. In

fact, the male medians for either skinfold fall

below the 5th percentile values for females.

In contrast to the greater skinfold thicknesses

among females, there is a greater skewness to be

seen, at any skinfold and at any age, among males

(see table 6). With five skinfolds and six age

groups, 30 skewness comparisons are possible;

greater values are seen among males in all 30.

(Note that this is a relative matter since greater

skinfold thicknesses occur among females.)

Race Differences

Tables 7-11 present the distributions of the

skinfolds for whites and Negroes separately. The

medians are graphed in figures 6-10. For the

— white

..—. Negro

~Fema’e

.—--”~ ‘ate

ol17 18

AGE IN YEARS

Figure 6. Median triceps skinfold of U.S. youths, by age, sex,

20

l--

— WII ihe

. . ... Negro

15

... .. .

#

10 . . . .

. ...”.”..

. ..-_.. o-....”

5

Female

Male

-1

12 13 14 15 16 17 1s

AGE IN YEARS

Figure 7. Median subscapular skinfold of U.S. youths, by age,

sex, and race.

limb skinfolds, whites have markedly greater

thicknesses than do Negroes of the same age and

sex. Within each sex, the shapes of the curves

joining the medians for the limb skinfolds are

quite similar; i.e., the 50th percentile values are

generally decreasing in males while increasing

in females. The increases in the medial calfskinfold from year to year are greater and more

regular in white than in Negro girls; the latter

display an irregular curve though the sample size

20 —

— White

-... Negro

.

E ,5

n

d

LL

g

Ym

~ ,0

a

Female

:

x

~ *

5

5 —

Male

z

<

. .. . .. .... ... .. .. .. .. .. . .. .. .... .. ... . .. . .. .. ... . ... .. ... .

0

Y

o I I I I I I

12 13 14 15 16 17 18

AGE IN YEARS

Figure 8. Median midaxillary skinfold of U.S. youths, by age,

sex, and race. and race.

7
20

-r ——White

.. . . . . Negro

~

CJ

15

0

“k:..-” ”-.................,. <,00... . .. . ... Female ,.. 2

z

....”

w . . . . . . . . . . . . . ....””

~ 10

= Male

$

I

...- . ... .. ..ooem.

......

; .............................................

o~12 13 14 15 16 17 18

AGE IN YEARS

Figure 9. Median suprailiac skinfold of U.S. youths, by age,

sex, and race.

of the Negroes is smaller, which may contribute

to the irregularity.

Racial differences in trunk skinfolds vary

with respect to the site being discussed. For the

median subscapular fold, no systematic differences are to be seen, in either sex, between whites

and Negroes. For the midaxillary, whites have

slightly greater medians than do Negroes, with

more consistency noted among boys. As far as

the suprailiac fold is concerned, racial differences

are the greatest of any of the three trunk skinfolds.

=Fema’e

-“<““”””------- .......................<.00 . . . . . . . . . . . . . . . ..< .000Male

I I I I I I

12 13 14 15 16 17 18

AGE IN YEARS

This difference is especially marked among boys,

with the white medians being on the order of 50

percent greater than those of Negro boys of the

same age group.

Skewness coefficients are presented for

whites and Negroes in table 12. As when the races

were combined, the trunk distributions are more

highly skewed than those of limb folds. However,

the magnitude of the trunk/limb dichotomy is

greater among whites.

Relationships ta Data from

Cycles 1 and II

The triceps and subscapular skinfolds were

measured in all three cycles of the HES and hence

have now been described throughout the age range

from 6 through 79 years. 516In figures 11 and 12 the

medians are graphed against age, males and females separately, for 6-21 years. (The 21.5 year

plot represents the midpoint of those subjects

18-24 years old.) The figures show the changes in

median skinfold from 6 years of age into the adult

period in both sexes, all races combined. The differences between the sexes in the thickness of both

skinfolds are clearly delineated and exist at all

ages.

For the triceps fold, the curves are, as noted

above, markedly different in shape for the two

sexes, the focus of the difference centering at

adolescence. From 6 years, the medians increase

17— /.” I

......

16 — Fem,k ..........””’”

... . ...

15 —

....”

...

#

2 ....”

g 14 — ....”

5 ...””

: 13

z

...””

% ,3 _

....”

...... ............

#

....”

s ,,

....”

E ....”

% ....”

E 10 .....”

:

/

9 _..””

8 —

$,, ,,, ,,, ,,, ,

I I I

6780 10 11 12 13 14 15 16 17 21 22

AGE IN YEARS

Figure 10. Median medial calf skinfold of U.S. youths, by age, Figure 11. Median triceps skinfold of U.S. males and females

sex, and race. 6-21 years of age.

8
Q*~ 10 11 12 13 14 15 16 17 21 22

AGE IN YEAflS

Figure 12. Median subscapular skinfold of U.S. males and

females 6-21 years of age.

in both boys and girls, boys reaching a maximum

thickness in the 11 and 12 year age groups; in

girls the medians level off at 10%-12% years.

Thereafter the sexual dimorphism increases

markedly. The decrease in median triceps thickness in males is such that, in the 15-17 year

groups, the medians are less than those observed

at 6-8 years. The 18-24 year group median indicates another increase in males from this late

adolescent “low” to a value of 12.0 mm., according to data from Cycle I, in the 25-34 year group.

Until llM years of age, the subscapular skinfolds increase in males and females in parallel

fashion, though females have consistently thicker

medians by about 25 percent. From 11%years on,

however, the sex differences increase, with females adding fat more rapidly than before, as inferred from changes in the medians. The apparent rate in males remains the same. Both sexes

continue to display increases into adulthood until

the 5th and 6th decades.

Correlations Among Skinfolds

Tables 13 and 14 present the correlations between pairs of skinfolds by age, sex, and race, as

well as for combined categories. Data from only

those individuals on whom all skinfolds were

measured were utilized, and the sample sizes are

therefore less than those given in tables 1-5.

For any pair of skinfolds, the correlation is

quite high and is greater than 0.6 for the 450

values of both tables except in seven cases, which

were in the 0.56-0.59 range. All values were

positive. Thus, there is a strong tendency for individuals who have a greater thickness of subcutaneous fat at one site to be correspondingly

fatter at other sites, regardless of their age, sex,

or race.

In all but a very few instances, the correlations among boys are higher than among girls,

indicating somewhat greater independence of skinfold thicknesses in girls from 12 through 17 years.

In fact, the seven low values referred to in the

preceding paragraph all occur in girls.

With respect to race, higher correlations

generally are to be found among Negro boys than

white boys of the same age. From the age-grouped

values of table 14 it can be seen that the v values

among Negro boys are higher than the corresponding ones for whites for all 10 skinfold pairs. Among

girls racial differences are not clear and no pattern emerges.

The correlations among all possible pairs of

skinfolds were analyzed, as shown in table 15, in

an attempt to discern patterns. Within each agesex-race group, the correlations for all pairs of

skinfolds were ranked from 1 (lowest) through

10 (highest). For example, among 12-year-old

males, the lowest correlation was noted for the

subscapular/medial calf skinfolds and the highest

for the subscapular/midaxillary skinfolds. The

ranks of each pair were summed for males and

for females; thus, the pair with the highest sum

would yield the highest correlations for the years

12-17, as determined by relative rankings.

As one might expect, the highest correlations

were to be found with correlations of one trunk

skinfold with another. Thus, among both males

and females, the subscapular/midaxillary correlation was the highest; in fact, this pair had the

highest ~’s for every age group in both males and

females. The triceps skinfold correlated highly

with the medial calf, though not as well as the

trunk folds correlated with each other. The triceps fold also correlated moderately well with the

three trunk sites. On the other hand, the correlations of the medial calf skinfold with the three

trunk folds were the lowest of all in both males

and females.

The rankings of individual skinfolds may be

determined by summing the ranks of all of the

9
correlation coefficients in which a particular one

appears. For example, adding the ranks of allr’s

involving the triceps fold, regardless of the other

skinfold, provides an overall indication of the

strength of the correlation of the triceps with the

other four. skinfolds. Among girls, the subscapular skinfold was associated with the highest

correlations with other skinfolds, while the midaxillary ranked second and the suprailiac third.

Among boys, the suprailiac fold was associated

with the highest values, while the midaxillary and

subscapular folds clustered together in the second

spot. However, the consistency of these observations is much higher among girls than among

boys.

Geographic Differences

Tables 16-20 present the skinfold distributions by geographic region, age, and sex. Racial

groups are combined and the composition of each

region reflects its own racial makeup. No real

differences are to be observed among the four

regions except that slightly smaller medians

tend to exist for children from the South. These

differences, however, are almost always less

than 1.0 mm. and may reflect the greater proportion of ,Negroes among the population of that

section of the country.

Triceps Skinfold Thickness by

Age and Weight

Tables 21-35 give the distribution of the triceps skinfold thickness by age for weight categories from below 30 to 100 kg. or more. Such

tables were also presented for the 6 to 11-yearold children of Cycle 11.6 Their utilit y stems from

the knowledge that a given body weight may contain a high or a low proportion of fat, and the

evaluation of this relationship in individual children is an important feature of a clinical examination. These tables allow an objective evaluation

of the individual relative to the triceps skinfold,

and their use is described in the report on Cycle

II skinfolds.6 As an example, it may be seen that

90 percent of 15-year-old girls weighing 55:60 kg.

(121-132 lb.) may have triceps skinfolds 9,6-

24.3 mm. thick. Obviously, within any weight

category, there will be striking variation in fatness, The consideration of triceps fold thickness

relative to weight, and weight relative to height~g

can help materially in the evaluation of the degree

of fatness.

Comparison With Other Studies

While it is possible to compare the HES

data to those from other studies, the significance

of such an exercise would, more often than not,

be uncertain and frequently comparisons might

even be meaningless. To compare the Cycle III

distributions to the results of other studies of

American youths would primarily test the sampling variability of the latter. The Health Examination Survey utilized the most sophisticated

methods possible to insure an accurate representation of the total U.S. population and of the

four geographic regions noted above. Other studies

have sampled far more restricted groups with

methods which could only increase sampling variability; hence, any differences noted would be difficult to interpret.

Likewise, to compare the Cycle 111data to

studies from elsewhere in the world would be to

ignore the fact that the amount of body fat is

highly responsive to the environment and, again,

one would be hard put to ascribe differences to

genetic factors, hereditary factors, or interactions of the two.

On the other hand, one detailed comparison

may be made and may prove informative even

though the interpretations of differences may be

difficult. Scott’s study 13 of children from the

London schools is noteworthy because of its

comprehensive nature, over 25,000 children being

measured. In addition, his data form one of the

core samples in the growth standards for British

childrenll widely used throughout the United

Kingdom. Figures 13 and 14 present the medians

and the 10th and 90th percentiles for the HES and

the London County Council (LCC) children for the

triceps and subscapular skinfolds (the two measured in the LCC survey) by age and sex.

The median triceps skinfolds are greater

among American youths of either sex than their

English age peers; though these differences are

small, they are consistent throughout the age

range 12-17 years. The reverse is, in general,

10
MALE

30

26

20

16

10

5

01

30

e Health ExaminationSurvey youths

,...., London County Council youths

25

20

Percentile ‘“%.. .. ..

.... . ... .. ..

15

““%. .. . .. ~oth

. . . ... .. . . . . . . . . . .. . . .

10

both

. . .. . . . . . . . . .. . . . . .. . .. . . . . . . .. . . . .. . .. . . .. . . . . . . . . ..

1oth 5

I I I I I I o

FEMALE

Percentile

~oth

. .. .. .

. .. ...

.. . . . . .

. . . .. .

.. . .. . . . . . . . . . .. . .. .

.. .

/...

.................

I I I I I I

12 13 14 15 16 17 18 12 13 14 15 16 17 18

AGE IN YEARS AGE IN YEARS

th Seth, and 9t)th percentiles. Figure 13. Comparison of triceps skinfold of U.S. and English youths: 10 ,

true for the subscapular skinfol~ the medians At the 10th percentile, London males display

are greater among the boys and girls of the higher values for lmth skinfolds. The same is true

London sample. This is in agreement with com- for the subscapular fold in females, but, in the

parisons made between the London and American case of the triceps, American females have higher

children between 6 and 11 years.6 values after the 13th year.

30

25

20

16

10

6

0

MALE

30 —

_ Health Examination Survey youths

.. . .. . London County Council youths I

25

20

Percentile

I

FEMALE

Percentile

~’oth

..

.

- /-=--/’’o’h ‘5 ..................................m..,,,. ........,. I10

... . . . . .. . . . . . . . . . .. . .. . . . . . . . . ... . . . . . . . . . . . . . . ...””

~oth

. . . . . .. . .

.. . .. . . . . . . . . . .. . . . . . . . . . .. . . . . . . . . .. ....”.

, Oth

5

[

Seth ...................

.....................................................

,Oth

-

I I I I I I ol12 13 14 15 16 17 1s 12 13 14 15 16 17 1s

I I I I I I

AGE IN YEARS AGE IN YEARS

Figure 14. Comparison of subscapular skinfold of U.S. and English youths: 10th, 50th, and 90th percentiles.

11
On the other hand, at the 90th percentile,

greater values are to be found among American

youths of similar age and sex, regardless of skinfold. These differences exceed, in some cases,

3.0 mm., and indicate that greater fatness is to be

found in the HES sample, compared to the London

sample, as evidenced by the skewing of the distributions.

The shapes of the curves constructed by

joining the values for similar percentiles tend to

be the same, with few differences occurring. Some

of the similarities may be of particular interest;

for example, the increase in the 90th percentile

value of the subscapular fold in 13-year-old boys

from both samples compared to adjacent values.

The parallel nature of the increase in English

and American boys suggests the operation of factors related to adolescent development.

DISCUSSION

The publication of these data on subcutaneous

fat distribution among U.S. children 12-17 years

old completes data for a 74-year age range and

provides comprehensive standards for the population from 6 years onward. This represents the

first available data of such magnitude which has

utilized sophisticated sampling techniques insuring a national probability sample. Thus, the

population of the United States, as it was in the

1960’s, is adequately depicted. Because the significant differences between Negroes and whites

in the amount of subcutaneous fat have now been

recognized, black and white American children

may now be evaluated on standards specific for

their own race.

Age and Sex Differences

The changes in subcutaneous fat that are

documented in this report for the adolescent years

as the child becomes an adult reveal significant

differences among the sites which are related to

sex. By and large, the increase in skinfold thickness in girls is persistent from 12 through 17

years. Among white girls the medians, at 17

years, for the midaxillary and suprailiac skinfolds are less than those for 16- year-olds. In

view of sample ~ize and sampling technique, this

is not likely to be fortuitous and, therefore, two

possible explanations exist. First, this may represent a true decrease; i.e., if the same girls

comprised the 16 and 17 year subgroups, these

differences would still exist and would be due to

a decrement in growth. Such a decrement might

occur, for example, from a conscious weight

reduction, through dieting, due to peer-group

pressure. However, since th’e HES sample is

cross sectional, this cannot be determined with

complete confidence. Second, some exogenous

factors may have affected the 17- year-olds differently than the 16-year- olds, thus leading to

differences in the medians. The absence of a

truly national catastrophe argues against this explanation.

Viewing the combined data of Cycles II and

HI, it appears that the triceps and subscapular

skinfolds among girls display similar growth patterns. There is a steady increase from 6 through

17 years, except for a plateau lasting for 2 years.

In the case of the triceps, this plateau occurs at

10-12 years and coincides with the period of rapid

growth in height as seen in figure 15. The plateau

for the subscapular skinfold occurs at ages 8-10

years.

Among boys, as noted earlier, fundamental

intersite differences in the pattern of age changes

are clear; these changes are related to other aspects of adolescent growth. Changes in trunk skinfolds (subscapular, midaxillary, suprailiac) show

an overall increase which seems to follow quite

well the observations made in Cycle II of the HES.

The decrease for boys in the triceps and

medial calf skinfolds is consistent for both sites,

and the rate of change for each age “group is

similar. This phenomenon has been observed by

other investigat~rs and is believed to be a genuine difference. For example, the findings of

Johnston and Ivialina14’15based on measurements

of tissue thicknesses on radiographs support

these findings as do those of other investigators.16’17

The decrease in limb fat in boys is clearly

related to their growth spurts. Changes in the

median thickness of the triceps and medial calf

skinfolds are closely related to the increased increments between mean heights associated with

the adolescent spurt.18 There is a definite relationship between the period of most rapid growth

in males and the decrease of triceps skinfold

thickness, which is shown in figure 15.

12
MALE

1.5

1.0 [

.1.0

k

‘1’

FEMALE

1.5

[

: +=’’;’nces’

.0.5

.1,0

4.0

F

3.5

3.0

2.5

2.0

1,5

1.0

0.5

0.0

...-.

... ..

... ..

.....

... .. .... %..

......... .. ...”

.....

....

:.

;...

.; Mean height

....

... ... .. . differ nce$

I I I I I 1 I I I I

6789 10 11 12 13 14 15 16 17 16

AGE IN YEARS

bxallld b?. IwOwrlndIlldnl awnnm

AGE IN YEARS

%OMnll by , thmwmkdm.kq svwap.

Figure 15. Comparison of pseudo velocity curve for triceps skinfold with pseudo velocity curve for height of U.S. males and females

6-17 years of age.

The meaning of the decrease in the thickness

of extremity fat in boys during adolescence is not

at all clear. As Tanner7 has noted, a decrease in

the thickness of the fat ring about the arm does

not have to mean a loss of fat, for an increase h

the volume of the underlying lean tissues, with a

constant fat volume, would result in a reduced

thickness of fat as it “inevitably.. would be

stretched out thinner” under these conditions.

The measurement of subcutaneous tissue widths,

either on X-rays or using skinfold calipers, tells

nothing of changes in the size or number of adipose tissue cells.

Additional information may be gained from the

calcula~ion of the estimated cross-sectional area

of fat in a circle at the level of the triceps skinfold, Since the circumference of the arm was

measured at this level, this parameter is easily

derived, assuming that the triceps skinfold, as a

double layer of adipose tissue, equals the diameter of fat at this site.

Table 36 presents the median cross-sectional areas of the upper arm and of the musclebone complex for each age group in Cycles II and

III by sex. Cross-sectional areas of fat have been

derived by subtraction of the medians. Girls display steadily increasing areas of fat from 6

through 15 years, paralleling the increase noted

in the thickness of the triceps skinfold. The area

of fat of the 16-year-old group is essentially the

same (6 mm.2 difference) as that of the 15-yearolds, while the 17- year -olds show an increase.

The derived cross-sectional areas of fat

among boys increase consistently through age 13.

For the next 2 years, i.e., ages 14 and 15, there

is a decrease, followed by a very slight increase

at 16 and a large increase at 17 years of age.

Several conclusions may be drawn from table

36. In girls no fat loss occurs in the upper arm

since both the triceps skinfold and the area of

fat increase with age. Because there is no further

increase in muscle-bone area after age 15, all

13
further increase in arm circumference seen in

table 36 must be due to increased fat.

In boys the decrease inderived cross-sectional areas of fat from ages 13 through 15, coupled with the decrease in median triceps skinfold

thickness, is evidence for an actual loss of fat in

this anatomical region. At other ages when the

triceps fold decreases but the cross-sectional

area of fat increases, there seems to be no absolute loss of fat, but instead a thinning of the

ring of fat due to expansion of underlying tissues.

The relative composition of the arm may be

examined by expressing the cross-sectional area

of fat as a percentage of arm area; this may be

seen in figure 16, again for Cycles II and 111data

combined. The differences between boys and girls

are quite striking. Before adolescence, the relative composition of the arm undergoes little

change, although girls have a higher percentage

cross- sectional area of fat. As they enter their

growth spurt, there is a relative decrease in fat

due to the larger increase in muscle and bone

(figure 15). As the rate of growth in muscle and

bone decreases, the relative fat content again

becomes greater.

The marked decrease in relative arm fat in

boys occurs from 12 through 16 years, The steepest decrease, from 13 through 15 years, is accompanied by an absolute loss of cross-sectional

area of fat (table 36).

Among girls, the derived cross-sectional —

“r

I Female

1

35 ....””

. .....

.... ............ ...+..+O ..””’”

..... ...””

... ....

30 ‘“””

....”

“.....”’

:

15

:Y0

6789 10 11 12 13 14 15 16 17 16

AGE IN YEARS

Figure 16. Percentage of cross-sectional area of arm comprised

of fat, by age and sex.

14

area of fat increased steadily from 6-17 years,

except at age 16, when it leveled off, and the

muscle-bone area increased from 6 through 15

years. Thus at ages 10-12 years, when the median

triceps fold remains unchanged, the increase in

upper arm circumference is due to the expansion

of the muscIe-bone mass rather than to fat. In

contrast, after 15 years, when the muscle-bone

area remains the same, the increase in arm circumference is due to an increase of subcutaneous

fat.

With respect to the five skinfolds, sexual

dimorphism during adolescence is greatest for the

triceps and the medial calf. The ratio of the medianfor females to that of males at 17 years is as

follows:

Suprailiac: 1.3

Midaxillary: 1.5

Subscapular: 1.6

Triceps: 2.1

Medial calfi 2.2

The female/male ratio for extremity skinfolds increases steadily during the adolescent

years. The relative sex difference in extremity

fat is about the same for the triceps as for the

medial calf, which is contrary to the suggestions

of Tanner, 7 although the data on which he has

based them may be subject to sampling error.

Race Differences

Differences between whites and Negroes reported for the Cycle 11sample6 persist throughout the ages of 12-17 years: whites have greater

medians for the triceps, when compared to Negro

children of the same sex and age, but not for the

subscapular skinfold. On the other hand the midaxillary skinfold medians are slightly greater in

white girls at ages 12-17 years, a difference

not observed in the 6-11 year old group.

The median medial calf skinfold changes

from 12 through 17 years in a manner similar to

that for the triceps in all four race/sex groups,

which is as expected.

The median thicknesses of the suprailiac

skinfold do not conform to the pattern of the subscapular or midaxillary folds, in that whites have

markedly greater values than do Negroes. However, Negro girls have greater medians than do

white boys of the same age, so that the influence

of sex-related factors is still strong, Apparently

the subcutaneous fat on the trunk displays a gradient as one moves from the back down and

around to the crest of the ilium with respect to
race; greater differences between the medians are

associated with more inferior skinfolds on the

trunk.

In the report on skinfolds from the HES

Cycle 11,6 it was suggested that extfemity fat

(as indicated by the thickness of the triceps skinfold) differed in whites and Negroes because of the

combined effects of racial and environmental factors, while trunk fat (as indicated by the midaxillary and subscapular folds) differed because of

the effects of environmental factors alone. This

was based on the observation that the racial dif-

“ferences in triceps fold thickness of children 6-11

years were of two degrees: the medians were

greater among whites than Negroes and there was

also greater skewness among whites, the comparisons being made to groups of the same age and sex.

At the same time, racial differences in the two

trunk skinfolds existed dy in the degree of skewness, whites showing the greater distortion of the

curves. It was suggested that environmental factors would tend to skew the curves and therefore

environmental differences would result in differentials in skewness. Racial (i.e., hereditary) dif -

ferences would result in a shift of the distribution with corresponding differences in the medians.

The data from Cycle III reinforce these conclusions, and they are combined with those from

Cycle II in table 37, which presents the results of

comparing the differences in the degree of skewness (given in table 12) between Negroes and

whites at each age and for all five skinfolds.

Greater skewness is seen in whites for the subscapular and midaxillary skinfolds in 31 of 46

comparisons which differed. Assuming, as before,

that skew results from environmental pressures,

and since the major differences between the races

in the skinfolds at these two sites are in the skewness and not in the medians, it is concluded that

Negro/white differences at these sites reflect

environmental factors.

Again with regard to skewness, the reverse

is true for the limb skinfolds. Greater asymmetry

is seen in the triceps and medial calf skinfolds

among Negroes h“ 26 of 35 comparisons. On the

other hand, in both sexes, the median triceps and

medial calf skinfolds are consistently greater itI

whites. The hereditary factors, which presumably

affect the medians, seem to work contrary to,

and to be more important than, environmental

factors.

The suprailiac skinfold distributions seem

more similar, in terms of asymmetry, to those

of the limbs than to those of the trunk, and one

would conclude that the greater median values

among whites therefore reflect hereditary mechanisms leading to fat deposition around the pelvic girdle.

Table 37 also shows the comparisons of

males and females, races combined. For every

skinfold, greater skewness is noted among males

more often than among females. If the greater

physical susceptibility to environmental factors of

males is considered, support is given to the assumption that skewness of skinfold distributions

is produced by environmental influences.

Finally, the five skinfolds may be ranked,

races and sexes combined, by their overall

skewness. This can be done by averaging all

skewness coefficients for a particular skinfold,

resulting in the following:

Midaxillafi: 5.37

Subscapular: 4.96

Suprailiac: 4.01

Triceps: 3.07

Medialcalf: 2.81

These values were computed only for 12-17 year

olds, since the suprailiac and medial calf skinfolds were not measured in Cycle II. In Cycle II,

the three skinfolds that were measured ranked as

above.

The above ranking of the five skinfolds, in

terms of their skewness, was consistent for all

four sex/race groups with the following exceptions: among Negro males, the suprailiac skinfold yielded the highest average skewness and,

among Negro females, there was a reversal of

the midaxillary and subscapular skinfolds. All of

this suggests that trunk fat, particularly that in

the subscapular and midaxillary regions, is more

responsive to the environment than limb fat and

that either of these two skinfolds may be a better

measure of adiposity in nutritional surveys than

is the triceps skinfold.

Correlations Among Skinfolds

The high intercorrelations among all skinfold pairs suggests that the thickness of the adipose layer in an individual at one site is strongly

dependent upon the thicknesses at other sites. The

generally high values for the midaxillary and

subscapular folds suggests that either may be the

best single skinfold during adolescent years to

use in estimating body fat, although it is clearly

15
better to measure othet-s as well, if at all possible. The subscapldar and triceps, the two folds

most frequently measured, probably pro-ride acceptable estimates of body fat. The nearness of

the midaxillary to the subscapular site suggests

that its addition would not add much more information. (Their correlations are also consistently

the highest.) The difficulty in measuring the

medial calf skinfold and the relatively low ?’

values argue against a high priority for its inclusion.

SUMMARY

This report presents and analyzes the distribution of skinfold measurements in United

States youths, 12-17 years of age, as estimated

from Cycle III of the Health Examination Survey.

The thickness of five skinfolds was measured—

triceps, subscapular, midaxillary, suprailiac, and

medial calf—and the results analyzed by age, sex,

race, geographic region, and in relation to youths

from outside the United States. As appropriate,

data from Cycle H have been included to present

a picture of changes in body fatness from 6 through

17 years.

At. every site, girls display greater skinfold

thicknesses than do boys of the same age. These

differences exist at all percentiles and for both

Negroes and whites, similar to those found in

Cycles I (18-79 years) and II (6-II years).

In both males and females, the skinfolds of

the trunk (subscapular, midaxillary, suprailiac)

increase in thickness with age from 12 through

17 years. In girls the median triceps skinfold,

after leveling off at ages 10-12 years, continues

to increase through 17, while in boys both the

triceps and the medial calf folds decrease steadily

from 12 through 16 years of age.

Since these patterns of change in the triceps

skinfold occur during the period of rapid adolescent growth, they were also examined by deriving the cross- sectional area of fat at the level

of the triceps skinfold for each individual from

6-17 years. In addition? the underlying musclebone mass was calculated from the upper arm

circumference and triceps thickness.

The leveling off of the median triceps skinfold in females at 10-12 years, seen in figure 11,

represents the counterpart to the reduction in

limb skinfold thickness among males. However,

the magnitude of the change is not at all comparable to that observed in males. Thus, it is

16

clear that the increase in upper arm circumference among females 10-12 years is due to an

increase of muscle and bone.

In boys, the area of fat at the level of the triceps fold actually decreased from 13 through 15

years of age, then increased from 16 throdgh 17

years. This decrease in cross-sectional area of

fat, along with the sharp decrease in triceps skinfold thickness at that time, indicates an actual

loss of arm fat at ages 13-15 years, which corresponds to the period of most rapid growth for

these boys. It appears that the decrease in

triceps fold thickness at other ages is due, not to

fat loss, but to the thinning of the fat ring caused

by the growth of the underlying muscle and bone.

Racial comparisons reveal greater median

skinfold thicknesses in whites than in Negroes of

corresponding age and sex for the triceps, medial

calf, and suprailiac folds, while no consi stent dif -

ferences were noted for the subscapular and midaxillary folds.

The greater skewness to the right of the subscapular and midaxillary distributions in whites,

considered in conjunction with the similarity of

the medians for whites and Negroes, suggests

that racial differences at these sites result

primarily from the operation of environmental

factors. At the other sites, both hereditary and

environmental factors seem to be operating.

The generally high correlations between

pairs of skinfolds indicate a tendency throughout the entire body to fatness or lean,less in the

individual. However, those correlations in which

one of the three trunk folds was involved tended

to be the highest, while those involving the medial

calf were the lowest.

It is concluded that the measurement of the

triceps and subscapular skinfolds, being the ones

most frequently taken, offer acceptable estimates

of body fat, although others may be desirable for

specific purposes. The midaxillary fold, due to

its high correlation with the subscapular, yields

no additional information. The high correlation

of the suprailiac with the subscapular, and its

relatively high error of measurement, suggest

that its use be reserved for specific purposes.

The high correlation of the medial calf with the

triceps, its low correlation with all others, and

its high error of measurement, argue against

its use, as a general rule. The apparent responsiveness of the subscapular fold to environmental factors, the acceptably lower errors of
measurement, and its high correlation with all ment in the study of adiposity caused by dietary

others, lead to the conclusion that it is prob- intake.

ably the single most useful skinfold measureREFERENCES

1Nation~ Center for Health Statistics: Plan and initial

program of the Health Examination Survey. Vital and Health

Statistics. PHS Pub. No. 1000-Series l-No. 4. Public Health

Service. Washington. U.S. Government Printing Office, July,

1965.

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Health Examination Survey: sample and response, United

States, 1960-1962. Vital and Health Statistics. PHS Pub. No.

1000-Series 1l-No. 1. Public Health Service. Washington. U.S.

Government Printing Office, Apr. 1964.

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and response results of a program of children’s examinations.

Vikd and Health Statistics. PHS Pub. No. 1000-Series l-No. 5.

Public Health Service. Washington. U.S. Government Printing

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Vitaf and Health Statistics. PHS Pub. No. 1000-Series l-No. 8.

Public Health Service. Washington. U.S. Government Printing

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girths, biachromial diameter, and selected anthropometric indices of adults, United States, 1960-1962, Vital and Health

S&stistics. PHS Pub. No. 1000-Sesies 1 l-No. 35. Public Health

Service. Washington. U.S. Government Printing Office, Feb.

1970.

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of children 6-11 years, United States. Vital and Health Statistics. Series 11-No. 120. DHEW Pub. No. (HSM) 73-1602.

Health Services and Mental Health Administration. Washington.

U.S. Government Printing Office, Oct. 1972.

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Blackwell Scientific Publications, 1962.

8Brozek, J.: Quantitative description of body composition: physical anthropology’s “fourth” dimension. Curr. Anthropol, 4:3-40, 1963.

9Mdina, R. M.: Qumtification of fat, muscle, and bone in

man. Clin. orthop. 65:9-38, 1969.

10seltzer, C. C., Goldman, R. F., and Mayer, J.: The triceps skinfold as a predictive measure of body density and body

fat in obese adolescent girls. Pediatrics 36:212-218,1965.

1 lTanner, J. M.: Standards for subcutaneous fat in British

chddren, Percentiles for thickness of skinfolds over triceps and

below scapula. Br. Med.]. 1:446450,1962.

~2National Center for Health Statistics: Height and

weight of children, United States. Vital and Heakh Statistics.

PHS Pub. No. 1000-Series 1l-No. 104. Public Health Service.

Washington. U.S. Government Printing Office, Sept. 1970.

JS.Scott, J. S.: Report on the Heights and Weights (and

other Measurements) of School Pupils in the County of Lotidon in 1959. London County Councfl, 1959.

14Johnston, F. E., and M&a, R. M.: Age changes in the

composition of the upper arm in Philadelphia children. Hum.

Biof. 38:1-21.1966.

15M~~a, R. M., and Johnston, F. E.: Relations between

bone, muscle, and fat widths in the upper arms and calves of

boys and girls studied cross-sectionally at ages 6 to 16 years.

Hum. Biol. 39:211-223, 1967.

~6Hea1d, F. p., Hint, E. E., Schwmtz, & Cook, C. D.,

Elliot, O., and Vajda, B.: Measuses of body fat and hydration

in adolescent boys. Pediatn”cs 31:226-239, 1963.

17Tanner, J. M.: Radiogs-aphic studies of body composition in children and adults, in J. Bro%ek, cd., Human Body

Composition, Approaches and Applications. London. Perganmn Press, 1965. pp. 211-236.

18 Nation~ Center for Health Statistics: Height =d

weight of youths 12-17 years, United States. Vital and Health

Statistics. Series 1l-No. 124. DHEW Pub. No. (HSM) 73-1606.

Health Services and Mental Health Administration. Washington.

U.S. Government Printing Office, Jan. 1973.

19National Center for Health Statistics: Sample design

and estimation procedures for a National-I-M&h Examination

Survey of children. Vital and Health Statistics. PHS Pub. No.

1000-Series 2-No. 43. Public Health Service. Washington. U23.

Government Printing Office, Aug. 1971.

20National Center for Health Statistics: Origin, program,

and operation of the U.S. National Health Survey. Vital and

Health Statistics. PHS Pub. No. 1000-Series l,No. 1. Public

Health Service. Washington. U.S. Government Printing Office,

Apr. 1965.

21National Center for Health Statistics: Replication: An

approach to the analysis of data from complex surveYs. vital

and Health Statistics. PHS Pub. No. 1000-Series 2-No. 14. Public Health Service. Washington. U.S. Government Printing Office, Apr. 1966.

22Nation~ Center for Health Statistics: A Regression

Scheme as a Solution to the Problem of Imputation, by S.

Lemeshow and T. Drizd, Technical Information Notes, No. 49.

Division of Health Examination Statistics, Rockville, Md. Jan.

31, 1973. Mimeographed.

23Nation~ Center for Health Statistics: Quality control in

a National Health Examination Survey. Vital and Health Statistics. Series 2-No. 44. DHEW Pub. No. (HSM) 72-1023. Health

Services and Mental Health Administration. Washington. U.S.

Government Printing Office, Feb. 1972.

17
LIST OF DETAILED TABLES

Table 1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

13.

14.

15.

16.

17.

18.

19.

20.

Triceps skinfold of youths by sex and age at last birthday: sample size, estimated population size, mean, standard deviations standard error of the mean, and

selected percentiles, United States, 1966-70------------------------------------

Subscapular skinfold of youths by sex and age at last birthday: sample size, estimated population size, mean, standard deviation, standard error of the means

and selected percentiles, United States, 1966-70--------------------------------

Midaxillary skinfold of youths by sex and age at last birthday: sample size, estimated population size, mean, standard deviation, standard error of the mean,

and selected percentiles, United States, 1966-70--------------------------------

Suprailiac skinfold of youths by sex and age at last birthday: sample size, estimated population size, mean, standard deviation, standard error of the mean,

and selected percentiles, United States, 1966-70--------------------------------

Medial calf skinfold of youths by sex and age at last birthday: sample size, estimated population size, mean, standard deviation, standard error of the mean,

and selected percentiles, United States, 1966-70--------------------------------

Skewness coefficients(difference between the 50th and 95th percentile divided by

the difference between the 5th and 50th percentile) by skinfold site, sex, and

age at last birthday of youths: United States, 1966-70--------------------------

Triceps skinfold of youths by race, sax, and age at last birthday: sample size,

estimated population size, mean, standard deviation, standard error of the mean,

and selected percentiles, United States, 1966-70-------------------------------

Subscapular skinfold of youths by race, sex, and age at last birthday: sample

size, estimated population size, mean, standard deviation, standard error of the

mean, and selected percentiles, United States, 1966-70--------------------------

Midaxillary skinfold of youths by race, sex, and age at last birthday: sample

size, estimated population size, mean, standard deviation, standard error of the

mean, and selected percentiles, United States, 1966-70--------------------------

Suprailiac skinfold of youths by race,sex,and age at last birthday: sample size,

estimated population size, mean, standard deviation, standard error of the mean,

and selected percentiles, United States, 1966-70--------------------------------

Medial calf skinfold of youths by race, sex, and age at last birthday: sample

size, estimated population size, mean, standard deviation, standard error of the

mean, and selected percentiles, United States, 1966-70--------------------------

Skewness coefficients (difference between the 50th and 95th percentile divided

by the difference between the 5th and 50th percentile) by skinfold site, race,

sex, and age at last birthday of youths: united States, 1966-70-----------------

Sample size and correlation coefficients for all possible pairs of skinfolds of

youths by race and sex: United States, 1966-70----------------------------------

Sample size and correlation coefficients for all possible pairs of skinfolds of

youths by race, sex, and age at last birthday: United States, 1966-70-----------

Rankings of correlation coefficients for all possible pairs of skinfolds of youths

with each race, sex, and age group: United States, 1966-70----------------------

Triceps skinfold of youths by geographic region, sex, and age at last birthday:

sample size, estimated population size, mean, standard deviation, standard error

of the mean, and selected percentiles, United States, 1966-70-------------------

Subscapular skinfold of youths by geographic region, sex, and age at last birthday: sample size, estimated population size, mean, standard deviation, standard

error of the mean, and selected percentiles, United States, 1966-70-------------

Midaxillary skinfold of youths by geographic region, sex, and age at last birthday: sample size, estimated population size, mean, standard deviation, standard

error of the mean, and selected percentiles, United States, 1966-70-------------

Suprailiac skinfold of youths by geographic region, sex, and age at last birthday: sample size, estimated population size, mean, standard deviation, standard

error of the mean, and selected percentiles, United States, 1966-70-------------

Medial calf skinfold of youths by geographic region, sex, and age at last birthday: sample size, estimated population size, mean, standard deviation, standard

error of the mean, and selected percentiles, United States, 1966-70-------------

Page

20

20

21

21

22

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

18
LIST OF DETAILEDTAELES-Con.

Table 21.

22.

23.

24.

25.

26.

27.

28.

29.

30.

31.

32.

33.

34.

35.

36.

37.

Triceps skinfold of youths 12-17 years of age weighing less than 30 kilograms,

by sex and age at last birthday: sample size, estimated population size, mean,

standard deviation, standard error of the mean, and selected percentiles, United

States, l966-7O----------------------------------L------------------------------

Triceps skinfold of youths 12-17 years of age weighing 30-34.9 kilograms, by sex

and age at last birthday: sample size, estimated population size, mean, standard

deviation, standard error of the mean , and selected percentiles, United States,

1966-70-------------------------------------------------------------------------

Triceps skinfold of youths 12-17 years of age weighing 35-39.9 kilograms, by sex

and age at last birthday: sample size, estimated population size, ,mean, standard

13d~;t#m, standard error of the mean, and selected percentiles, United States,

---------------------------------------------------------..--------------

Triceps skinfold of youths 12-17 years of age weighing 40-44.9 kilograms, by sex

and age at last birthday: sample size, estimated population size, mean, standard

deviation, standard error of the mean , and selected percentiles, United States,

1966-70-------------------------------------------------------------------------

Triceps skinfold of youths 12-17 years of age weighing 45-49.9 kilograms, by sex

and age at last birthday: sample size, estimated population size, mean, standard

deviation, standard error of the mean , and selected percentiles, United States,

1966-70-------------------------------------------------------------------------

Tricepsskinfoldof youths 12-17 years of age weighing50-54.9kilograms, by sex

and age at last birthday: sample size, estimated population size, mean, standard

deviation, standard error of the mean , and selected percentiles, United States,

1966-70-------------------------------------------------------------------------

Triceps skinfold of youths 12-17 years of age weighing 55-59.9 kilograms, by sex

and age at last birthday: sample size, estimated population size, mean, standard

deviation, standard error of the mean

1966-70

, and selected percentiles, United States,

--------------------------------------------.----------------------------

Triceps skinfold of youths 12-17 years of age weighing 60-64.9 kilograms, by sex

and age at last birthday: sample size,

deviation,

estimated population size, mean, standard

standard error of the mean, and selected percentiles, United States.j

1966-70-------------------------------------------------------------------------

Triceps skinfold of youths 12-17 years of age weighing 65-69.9 kilograms, by sex

and age at last birthday: sample size, estimated population size, mean, standard

deviation, standard error of the mean , and selected percentiles, United States,

1966-70-------------------------------------------------------------------------

Triceps skinfold of youths 12-17 years of age weighing 70-74.9 kilograms, by sex

and age at last birthday: sample size, estimated population size, mean, standard

deviation, standard error of the mean , and selected percentiles, United States,

1966-70-------------------------------------------------------------------------

Triceps,skinfold of youths 12-17 years of age weighing 75-79.9 kilograms, by sex

and age at last birthday: sample size, estimated population size, mean, standard

deviation, standard error of the mean , and selected percentiles, United States,

1966-70-------------------------------------------------------------------------

Triceps skinfold of youths 12-17 years of age weighing 80-84.9 kilograms, by sex

and age at last birthday: sample size, estimated population size, mean, standard

deviation, standard error of the mean, and selected percentiles, United States,

1966-70-------------------------------------------------------------------------

Triceps skinfold of youths 12-17 years of age weighing 85-89.9 kilograms, by sez

and age at last birthday: sample size

deviation, standard error of the mean

, estimated population size, mean, standard

, and selected percentiles, United States,

1966-70-------------------------------------------------------------------------

Triceps skinfold of youths 12-17 years of age weighing 90-99.9 kilograms, by sex

and age at last birthday: sample size, estimated population size, mean, standard

deviation, standard error of the mean , and selected percentiles, United States,

1966-70-------------------------------------------------------------------------

Triceps skinfold of youths 12-17 years of age weighing 100 kilograms or more, by

sex and age at last birthday: sample size,estimated population size,mean, standard deviation,standard error of the mean,and selected percentiles,United States,

1966-70-------------------------------------------------------------------------

Area of arm at triceps, estimated area of muscle and bone, and estimated area of

fat for males and females 6-17 years of age: United States, 1963-70-------------

Comparison of skewness ratios between races and sexes for skinfolds of children

and youths: United States, 1963-70----------------------------------------------

Page

37

37

38

38

39

40

41

42

43

44

45

46

47

48

49

50

51

19
Table 1. Triceps skinfoldof youthsby sex and age at last birthday:sample size, estimated

ulation size,mean, standarddeviation, standarderror of the mean, and selectedpercent%;

United States,1966-70

Percentile I 5th 10th 25th 50th 75th 90th 95th

Sex and age n N 1s

Male In millimeters

10.7

10.5

9.5

;.:

9:0

12.9

13.6

14.8

15.8

16.5

16.5

5.83

5.85

5,60

5.11

;.:;

.

5.82

6.07

6.13

6.60

6.91

6.24

0.27

0.25

0>.27

0.25

0.28

0.24

0.29

0.28

0.23

0.37

0.41

0.41

::;

4.2

4.3

4.2

4.1

::;

7.1

7.4

U

5.5

2:;

4.7

4.7

4.6

;.;

8:3

;::

9.6

13.3 19.6

12.9 19.3

12.0 17.1

10.7 15.8

11.1 15.8

11.4 15.6

23.3

22.6

20.8

20.7

20.2

20.5

25.2

25.5

26.7

29.4

29.7

29.1

12 years-----------------

13 years-----------------

14 years-----------------

15 years-----------------

16 years-----------------

17 years-----------------

643

626

617

613

555

489

547

582

586

502

535

468

2,032

2,006

;:;$:

1,833

1,764

1,970

1,946

1,901

1,848

1,787

1,743

6.8

::;

5.8

5.8

5.5

::;

10.7

11.6

11.8

12.1

9.4

;.:

7:6

7.5

7.5

11.8

12.4

14.0

14.8

15.6

15.8

Female

16.0 22.2

17.1 22.8

18.5 23.3

;;.: ;:.;

20:5 25:0

12 years-----------------

13 years-----------------

14 years-----------------

15 years-----------------

16 years-----------------

17 years-----------------

NOTE: ~= sample size; N=estimated number of youths in populationin thousands; ~-mean;

S = standard deviation; S2= standard error of the mean.

Table 2. Subscapularskinfoldof youthsby sex and age at last birthday: sample size, estimated

populationsize,mean, standarddeviation,standarderror of the meanjand selectedpercentiles,

United States,1966-70

Sex and age

—

?l

—

543

526

;18

i13

556

i87

;46

582

586

501

536

i69

N

2,032

2,006

1,951

1,900

1,836

1,758

1,968

1,946

1,901

1,845

1,789

1,746

Percentile

z s SE

5th 10th 25th 50th 75th 90th 95th

In millimeters

12

13

14

15

16

17

12

13

14

15

16

17

7.3

8.1

8.1

8.3

8.5

9.3

1;:;

11.5

12.4

13.1

13.3

5.44

6.18

5.62

5.42

4.92

5.16

6.22

6.84

6.72

7.23

7.56

7.72

0.22

0.22

0.29

0.22

0.22

0.24

0.27

0.36

0.25

0.32

0.39

0.49

t:

4.2

4.5

5.0

5.1

4.5

5.0

5.5

::;

6.2

4.1

4.3

4.6

5.1

5.3

5.6

5.1

5.3

6.2

6.4

6.8

6.7

4.7

5.1

5.4

5.7

6.1

6.5

?;

;:?

8.1

8.2

5.7

6.2

6.5

6.8

7.2

7.7

U

J::

10.8

11.3

13.7

16.1

14.2

13.7

13.8

16.4

18.8

20.9

20.3

24.0

24.4

23.0

20.8

22.1

20.4

20.4

19.5

21.4

23.8

25.6

25.8

28.9

30.2

30.6

years-----------------

years-----------------

years-----------------

years-----------------

years-----------------

years-----------------

7.6

8.5

8.5

8.8

9.2

10.6

11.7

12.7

13.7

15.1

15.7

17.0

Female

years-----------------

years-----------------

years-----------------

years-----------------

years-----------------

years-----------------

NOTE: n= sample size; ~= estimatednumber of youths in populationin thousands; ~=mean;

S = standard deviation; SE =standard error of the mean.

20
Table 3. Midaxillary skinfold of youths by sex and age at last birthday: sample size, estimated

Dowlation size, mean, standard deviation, standard error of the meaqand selected percentiles,

United States, 1966-70

Sex and age n N

I

Es

90th ]95th

Male In millimeters

12

13

14

15

16

17

12

13

14

15

16

17

643

626

617

613

556

488

546

582

586

502

536

469

2,032

2,006

1,947

1,900

1,836

1,762

1,967

1,946

1,901

1,847

1,789

1,746

4.94

5.42

.5.72

5.55

4.82

5.71

5.92

6.29

6.17

7.00

6.94

6,91

0.20

0.18

0.30

0.23

0.24

0.30

0.26

0.33

0.22

0.34

0.34

0.48

4.7

4.9

5.1

5.4

5.5

5.7

6.7

:::

8.5

:::

6.6

6.9

6.8

7.3

7.3

7.9

10.6

11.3

12.6

13.2

13.6

13.7

13.4

13.5

13.6

12.5

12.4

14.8

17.1

18.2

19.5

21.9

21.4

20.7

19.1

19.1

19.3

17.9

17.4

22.2

23.3

23.4

22.8

26.8

27.7

24.9

years-----------------

years-----------------

years-----------------

years-----------------

years-----------------

years-----------------

6.3

H

::;

7.6

8.6

1%;

10.9

11.2

11.0 I

3.1 3.2

3.1 3.4

3.2 ;.;

3.4

3.4 3:8

3.6 4.1

4.2

::: 4.5

4.4 4.9

4.5 5.2

5.4

::; 5.4

N

4.2

4.4

4.5

4.6

5.1

5.6

6.3

6.4

6.8

6.6

J?emale

years-----------------

years-----------------

years-----------------

years-----------------

years-----------------

years-----------------

NOTE : n =sample size; N=estimated number of youths in population in thousands; ~=mean;

S =standard deviation; ~ = standard error of the mean.

Table 4. Suprailiac skinfold of youths by sex and age at last birthday: sample size,

Modulation size. mean, standard deviation,

estimated

standard error of the mean,and selected percentiles,

Un~ted States, 1966-70

Sex and age x

11.8

12.2

12.1

12.6

12.6

13.9

13,9

14.7

15.5

16.3

16.2

15.9

N

Percentile

5th 10th 25th 50th 75th 90th 95th

n

J-S SF

Male In millimeters

640

626

618

613

555

487

545

582

586

502

536

468

2,027

2,006

1,951

1,900

1,834

1,757

1,963

1,946

1,901

1,847

1,789

1,742

9.14

9.49

9.39

9.03

8.52

9.83

8.36

8.22

7.75

8.42

8.12

8.64

0.33

0.35

0.43

0.37

0.47

0.55

0.37

0.37

0.34

0.50

0.49

0.54

:::

4.2

::;

5.0

4.7

;.:

6:3

6.7

6.1

4.4

2:?

5.3

5.5

5.5

5.6

6.4

7.3

:::

7.4

5.7

:.:

6:8

7.1

7.2

u

10.1

10.3

10.6

10.2

8.3

8.7

8.8

9.4

1::?

1.2.2

13.1

14.1

14.8

14.7

13.8

15.3

15.3

14.6

15.1

16.2

17.6

18.7

18.8

20.3

21.4

20.3

20.7

26.6

27.6

26.4

26.4

25.4

29.6

25.5

26.2

26.6

29.3

28.3

28.3

31.6

33.8

33.4

32.3

32.3

38.1

30.8

32.4

31.2

:$:

32:8

years-----------------

years-----------------

years-----------------

years-----------------

years-----------------

years-----------------

Female

years-----------------

years-----------------

years-----------------

years-----------------

years-----------------

years-----------------

NOTE: n =sample size; ~= estimated number of youths in population in thousands; ~=mean;

S = standard deviation; “Sz= standard error of the mean.

21
Table 5. Medial calf skinfold of youths by sex and age at last birthday: sample size, estimsted

population size, mean, standard deviation

United States, 1966-70

, standard error of the mean,and selected percentiles,

Sex and age

12 years-----------------

13 years-----------------

14 years-----------------

15 years-----------------

16 years-----------------

17 years-----------------

Female

12 years-----------------

13 years-----------------

14 years-----------------

15 years-----------------

16 years-----------------

17 years-----------------

n

—

639

620

612

609

553

487

536

579

579

497

530

46o

iv

2,021

1,980

1,934

1,888

1,828

1,758

1,933

1,936

1,876

1,830

1,768

1,710

Percentile

z s L$

5th 10th 25th 50th 75eh 90th 95th

In millimeters

12.0

12.3

11.3

10.7

10.0

9.9

15.3

16.6

17.8

18.7

19.0

19.7

6.87

7.07

6.98

6.41

5.81

6.18

6.76

7.17

7.01

7.75

7.28

7.70

0.28

0.33

0.33

0.31

0.29

0.29

0.27

0.31

0.35

0.51

0.34

0.47

4.8

5.0

4.7

4.6

4.1

4.0

7.3

7.5

8.7

8.8

9.4

9.4

5.4

5.7

5.3

M

4.5

8.5

1::;

10.4

11.1

11.0

;.;

6:7

6.7

6.2

6.0

LO.8

L1.7

L2.6

L3.8

L4.O

L4.1

10.5

10.6

9.6

9.2

8.4

8.5

14.1

15.5

16.8

17.7

18.5

18.9

15.6

15.6

14.0

13.1

12.5

12.2

18.7

21.3

22.5

22.8

23.4

24.0

21.5

22.4

20.3

19.4

18.7

18.5

24.5

26.5

27.9

28.8

28.6

30.6

26.4

26.9

25.4

24.4

22.3

22.6

30.2

31.2

30.6

34.5

31.7

34.4

NOTE : 7Z= sample size; N= estimated number of youths in population in thousands; ~=mean;

s = standard deviation; S% = standard error of the mean.

Table 6. Skewness coefficients (difference between the 50th and 95th percentile divided by the

difference between the 5th and 50th percentile) by skinfold site, sex, and age at last birthday

of youths: United States, 1966-70

Sex and age

12

:;

15

16

17

12

13

14

15

16

17

years--------------------------

years--------------------------

years--------------------------

years--------------------------

years--------------------------

years--------------------------

Female

years--------------------------

years--------------------------

years--------------------------

years--------------------------

years--------------------------

years--------------------------

Triceps

3.18

2.94

3.60

3.98

3.87

3.83

2.36

2.18

1.83

1.97

1.81

1.70

Subscapular

7.58

7.49

5.95

5.83

5.51

5.25

4.88

4.89

‘3.85

4.18

4.25

3.79

Skinfold

tidaxillary

8.60

8.04

7.58

6.25

5.60

7.84

5.46

4.68

3.56

4.55

4.06

3.86

Wprailiac

5.15

5.44

5.40

4.87

4.45

5.00

2.49

;.::

2:28

2.22

2.47

fedial calf

2.73

2.91

3.20

3.27

3.24

3.19

2.36

1.97

1.69

1.87

1.47

1.63

22
Table 7. Triceps skinfold of youths by race, sex, and age at last birthday: sample size, estimated population size, mean. standard deviation, standard error of the mean, and selected percentilksi United States, 1966-70

Race, sex, and age

12

13

14

15

16

17

12

::

::

17

12

13

14

15

16

17

H

14

15

16

17

m

Male

years---------------

years---------------

years---------------

years---------------

years---------------

years---------------

Female

years---------------

years---------------

years---------------

years---------------

years---------------

years---------------

NEGRO

Male

years---------------

years---------------

years---------------

years---------------

years---------------

years---------------

Female

years---------------

years---------------

years---------------

years---------------

years---------------

years---------------

n

540

542

526

525

495

417

455

490

484

424

440

392

101

80

88

H

69

88

J:

73

93

74

N

1,747

1,729

1,683

L,646

1,591

1,528

1,685

1,667

1,633

1,592

1,540

1,500

280

262

256

241

231

225

272

275

266

235

243

237

I

X5

11.0

10.8

9.8

9.3

9.1

9.2

13.0

13.8

15.1

16.1

16.8

16.8

8.7

8.5

n

7.1

7.7

12.2

12.0

13.6

14.1

14.9

14.5

5.82

5.81

5.59

5.29

5.11

5.$7

5.78

5.87

6.08

6.65

6.72

6.24

5.19

5.82

5.39

3.08

3.26

5.11

6.16

6.95

6.35

5.88

7.87

5.85

0.28

0.27

0.28

0.27

0.31

0.25

0.34

0.31

0.26

0.37

0.40

0.43

0.59

0.65

0.69

0.34

0.45

0.59

0.66

0.61

0.56

0.64

1.54

1.01

5.2

4.8

4.3

4.3

4.2

4.1

6.1

6.6

7.3

7.5

8.1

8.5

3.8

3.6

3.6

:::

4.2

6.0

6.0

5.5

7.2

7.0

7.1

In millimeters

5.7

;::

4.8

5.0

4.5

7.1

::;

8.8

1;::

4.7

4.2

4.1

4.2

4.3

4.6

6.5

6.3

6.7

8.2

7.6

7.6

7.2

::;

:::

5.6

9.2

1;:;

12.0

12.3

12.4

5.6

M

5.1

4.9

5.3

7.7

1;:;

10.2

9.6

10.7

9.7

::;

7.8

7.6

7.7

12.0

12.7

14.2

15.1

16.0

16.3

7.4

:::

6.4

H

10.6

9.8

12.5

12.8

13.1

13.4

13.6

13.4

12.5

11.2

11.6

11.6

16.0

17.2

18.7

20.0

21.2

20.8

10.3

10.3

8.4

u

8.5

16.2

13.6

17.3

17.9

17.8

18.2

19.8

19.7

17.4

16.4

16.5

15.8

22.1

22.7

23.5

25.4

25.5

25.3

15.3

15.6

14.2

10.6

11.7

14.0

22.5

23.9

22.1

22.7

26.4

23.3

23.2

22.6

21.2

21.3

20.5

20.7

25.1

25.4

26.8

29.9

29.1

29.5

23.2

25.2

19.2

14.7

12.8

15.8

25.6

27.2

24.6

25.8

31.5

25.8

NOTE: n = sample size; l/= estimated number of youths in population in thousands; ~= mean;

s G standard deviation; S% = standard error of the mean.

23
Table 8. Subscapular skinfold of youths by race sex, end a e at’last birthday: sample size, estimated population size, mean, standard deviat$on, standar/?error of the mean, end selected percentiles, United States,1966-70

Race, sex, end age

12

13

14

15

16

17

12

;:

15

16

17

12

13

14

15

16

17

12

13

14

15

16

17

WHITE

~

years---------------

years---------------

years---------------

years---------------

years---------------

years---------------

Female

years---------------

years---------------

years---------------

years---------------

years---------------

years---------------

NEGRO

&

years---------------

years---------------

years---------------

years---------------

years---------------

years---------------

Female

years---------------

years---------------

years---------------

years---------------

years---------------

years---------------

n

540

542

527

525

496

415

454

490

484

423

g;

101

80

88

84

z

H

101

‘E

74

N

1,747

1,729

1,686

1,646

1,594

1,522

1,682

1,667

1,633

1,588

1,542

1,502

280

262

256

241

231

225

272

275

266

235

243

237

]

z

7.4

8.2

8.2

8.5

:::

L;::

1.1.6

L2.6

L2.9

L3.2

6.3

7.5

;:;

;::

10.4

10.5

11.3

L1.9

13.8

13.4

1

s

5.46

6.31

5.67

5.67

5.13

5.04

6..16

6.92

6.80

7.41

7.36

7.79

3.92

5.30

5.29

2.89

3.14

5.98

6.69

6.40

6.25

6.04

8.72

7.27

).22

3.24

).30

3.24

3.26

3.26

Q.34

Q.41

CI.26

0.36

0.42

0.52

0.44

0.54

0.78

0.32

0.26

0.69

0.91

0.51

0.49

;.;;

1:05

Percentile

jth 10th 25th 50th 75th 90th 95th

2:

M

5.1

5.1

::$

5.5

5.8

6.2

6.2

4.1

4.2

4.1

4.4

4.3

5.2

4.6

;.;

6:2

6.1

6.9

In millimeters

4.1

~.:

5:1

5.3

5.6

5.0

u

6.4

6.8

6.6

4.2

4.4

4.4

4.8

4.7

5.5

5.3

5.7

6.4

6.7

7.1

7.3

4.7

5.1

5.4

i?:;

6.5

5.8

6.5

7.4

:::

8.2

4.7

5.1

5.2

5.4

5.6

6.6

6.6

7.0

:::

8:3

5.7

6.2

6.5

6.9

7.2

7.8

::;

L;:;

10.8

L1.2

5.5

6.2

6.3

6.4

7.3

7.6

8.4

8.6

1::2

10.5

12.3

w

!3:;

1::;

11.6

12.8

13.8

15.3

15.5

17.0

6,5

7.6

n

%:

11.8

11.6

13.6

13.,4

16.4

16.0

14.0

16.5

14.6

14.8

15.0

17.1

18.6

21.3

20.4

24.4

24.0

23.4

1?:2

10.5

1::;

11.9

20.5

18.7

18.1

21.5

26.6

22.1

21,1

22.3

20.6

21.3

20.5

22.0

23.7

25.5

26.3

30.0

29.8

31.0

16.5

17.2

15.3

11.7

12.3

20.7

24.6

30.0

25.1

26.0

32.8

30.5

NOTE: n= sample size; N= estimated number of youths in population in thousands; ~=mean;

S.= standard deviation; SE= standard error of the mean.

24
Table 9. Midaxillary skinfold of youths by race sex, and a e at last birthday: sample size, esti.matedpopulation size, mean, standard deviation, standar8 errorof the mean, and selected percentiles,United States,1966-70

Race, sex, and age

W-E

Male

years---------------

years---------------

years---------------

years---------------

years---------------

yeare---------------

Female

years---------------

years---------------

years---------------

yeara---------------

years---------------

years---------------

NEGRO

Male

years---------------

years---------------

veals---------------

15 ~ears---------------

16 years---------------

17 yeara--------------

Female

12 yeara---------------

13 years---------------

14 years---------------

15 years--.-..-------

~6 years ------------

17 years---------------

‘n

540

542

526

525

496

416

454

490

484

424

;:;

101

%

84

:;

88

1!:

;:

74

N

1,747

1,729

1,682

1,646

1,594

1,525

1,681

1,667

1,633

1,590

1,542

1,502

280

262

256

241

231

225

272

275

266

235

243

237

6.5

6.8

6.9

7.2

7.0

7.8

:::

10.3

11.1

11.4

11.1

4.9

5.r

H

u

8.8

%:

.:::

.0.1

5.01

5.57

5.92

5.84

5.01

5.65

5.91

6.33

6.28

7.13

7.06

7.11

3.24

4.39

$.::

2:98

6.06

6.02

6.03

5.39

6.02

6.02

5.53

0,22

0.20

0.33

0.26

0.28

0.34

0.34

0.36

C&J

0:38

0.52

0.36

0.44

0.54

0.19

0.34

0.72

0.73

0.56

0.36

0.48

0.91

0.64

Percentile

5th 10th 25th 50th 75th 90th 95th

In millimeters

3.0

3.2

3.2

3.4

3.5

3.6

:::

:.:

.

:::

3.1

3.0

;:;

3.2

3.5

3.7

2:?

:.;

5:0

3.2

H

:::

4.1

4.2

4.5

5.1

5.2

5.6

5.4

3.2

3.2

3.2

3.5

:::

4.3

4.2

:::

;.;

.

:::

4.2

4.4

4.5

4.6

5.1

2:;

6.5

6.9

6.7

3.5

:::

4.2

4.3

4.3

5.4

;:;

6.1

6.1

6.2

4.8

5.0

5.2

5.5

5.6

5.8

6.6

;::

R

8.8

4.2

4.7

2::

:::

H

8.3

7.6-

:::

6.8

7.1

7.1

7.6

:::

10.6

11.5

12.8

13.4

13.7

13.8

5.1

5.8

H

%!

9.8

13::

11.4

11.7

13.7

14.2

13.8

14.3

13.4

13.2

15.1

16.8

18.2

20.1

22.5

21.6

21.1

1;:;

8.2

7.2

::;

17.3

18.3

16.7

19.2

21.4

18.0

19.6

19.5

19.8

19.7

18.3

22.4

23,5

23.3

23.2

27.4

28.2

26.2

13.2

15.2

;:.:

.

1:::

22.5

23.8

21.1

23.4

23.5

21.3

NOTE: n = sample size;N= estimated number of youths in population in thousands; ~- mean;

s = standarddeviation;& = standarderror of the mean.

25
!fable10. Suprailtacskinfoldof youtheby race, sex, and age at last birthday:samplesize, estimated populationsike,mean, standarddeviation,standarderrorof themean, and selectedpercentiles,United States,1966-70

Race, sex, end age

—

Male

years -------------

years -------------

years-------------

years-------------

years -------------

years -------------

Female

years -------------

years-------------

years-------------

years-------------

years-------------

years-------------

NEGRO

Male

years-------------

years-------------

years-------------

years-------------

years-------------

years-------------

Female

years-------------

years-------------

years-------------

years-------------

years-------------

years-------------

n

538

542

527

525

495

415

453

490

484

424

441

392

100

80

88

84

57

69

::

101

;:

74

N

1,744

1,729

1,686

1,646

1,592

1,520

1,677

1,667

1.633

1,590

1,542

1,499

278

262

256

241

231

225

272

275

266

235

243

237

z

12.3

12.6

12.6

13.2

13.2

14.4

13.9

14.9

15.7

16.7

16.2

16.1

:::

9.0

;::

9.9

13.6

13.2

14.4

14.3

15.9

14.6

8

9.25

9.63

9.49

9.28

8.75

9.92

8.20

8.06

7.78

8.51

7.95

8.66

6.86

8.15

8.22

5.49

5.75

8.27

9.27

9.09

7.48

7.50

9.20

8.42

8X

.

0.32

0.40

0.48

0.38

0.52

0.64

0.48

0.41

0.38

0.56

0.51

0.57

0.90

1.00

1.16

0.59

0.50

0.82

1.23

0.90

0.73

;.;;

0:98

Percentile

5th 10th 25th 50th 75th 90th 95th

I I I I I 1

ti millimeters

i:;

4.3

5.1

5.1

5.2

4.9

5.5

6.3

6.6

7.0

6.2

H

:::

4.1

4.3

4.0

2;

2;

5.5

4.5

4.8

5.0

5.6

5.7

5.8

5.6

6.7

7.4

7.6

8.2

7.4

:.;

4:1

~:;

.

5.2

2:!

6.4

6.9

7.2

5.9

6.1

6.5

7.2

7.2

7.6

7.7

1;:$

10.5

10.8

10.2

4.9

5.0

5.2

;:;

5.5

;::

8.6

;::

9.5

9.1

9.1

Q:::

10.3

11.1

12.3

13.4

14.2

14.9

15.1

14.1

6.2

6.6

6.8

6.5

;::

11.3

10.9

13.7

;;.;

12:8

16.5

16.2

15.6

15.7

16.8

18.3

18.7

19.3

20.5

22.1

20.2

20.9

1?::

1;::

10.8

10.5

18.7

17.0

18.7

18.2

21.3

17.7

;;.;

27:5

27.6

25.9

30.2

25.5

26.1

26.8

29.7

27.2

28.6

18.2

22.4

15.6

13.4

15.4

19.8

25.8

27.7

25.4

23.8

30.8

24.7

31.8

34.4

33.6

34.2

32.8

38.3

30.8

32.0

31.3

34.5

31.9

33.0

23.5

33.3

26.1

23.4

19.6

26.6

32.3

36.6

30.2

29.5

35.5

30.4

NOTE: tl. sample size; I?-estimatednumber of youths in populationin thousends; X. mean;

8 = standarddeviation;SE= standarderror of the mean.

26
Table 11. Medial calf skinfold of youths by race, sex, and age at last birthday: sample size, estimated population size, mean, standard deviation, standard error of the mean, and selected ~ercentiles, United States, 1966-70

Race, sex, and age

WHITE

Male

years---------------

years---------------

years---------------

years---------------

years---------------

years---------------

Female

years---------------

years---------------

years---------------

years---------------

years---------------

years---------------

NEGRO

Male

years---------------

years---------------

yeara---------------

years---------------

yeara---------------

years---------------

Female

years---------------

years---------------

years---------------

years---------------

years---------------

years---------------

n

537

537

522

522

493

415

450

487

478

420

435

389

100

;?

83

:;

;:

100

;;

70

N

L,738

L,714

L,672

L,637

L,586

L,521

1,667

L,657

1,610

.,576

!,521

!,487

278

251

253

238

231

225

253

275

263

233

243

219

12.5

12.8

11.8

11.2

10.4

10.3

15.6

17.1

18.2

19.4

19.5

20.5

::;

8.2

7.0

;:;

13.1

14.0

15.2

14.4

16.4

14.2

6.90

6.98

7.01

6.57

5.98

6.15

6.77

7.07

7.01

7.78

7.02

7.72

5.00

6.79

5.99

3.48

3.38

5.91

5.42

7.25

5.41

5.12

3.27

k.97

In millimeters

0.28

0.37

0.38

0.34

0.32

0.32

0.32

0.36

0.40

0.57

0.42

0.53

0.69

0.82

0.80

0.36

0.43

0.70

0.84

0.58

0.47

0.56

1.52

0.68

5.2

5.5

::;

4.2

4.2

7.5

7.7

;:$

LO.3

LO.2

3.6

::!

4.2

3.5

3.3

::;

;::

7.6

7.9

2::

5.6

5.5

::;

H

LO.5

L1.O

11.6

11.7

::;

4.3

4.5

4.1

3.6

7.5

;:;

H

8.5

;:;

7.1

7.2

::2

:1.3

!2.3

.3.1

.4.5

.5.0

.5.5

5.2

5.2

5.2

H

4.9

9.7

;::

0.6

,1.0

1.0

11.1

11.3

10.2

10.0

8.7

8.8

14.4

15.9

17.3

18.4

19.2

20.0

;::

:::

::;

11.4

11.9

14.5

13.8

14.3

13.4

16.2

16.1

14.9

13.5

13.3

12.5

19.6

21.7

23.1

23.4

23.8

24.7

10.6

10.2

9.6

;:;

8.4

15.8

17.0

20.2

17.1

2.9.7

17.9

21.9

22.8

20.7

20.3

19.6

19.1

24.7

26.5

28.4

30.2

28.8

31.2

16.1

17.4

12.4

10.7

L1.7

3.6.2

20.8

24.6

25.3

24.2

25.9

21.2

26.8

27.5

25.4

25.1

22.6

23.0

30.4

31.4

30.9

35.6

31.6

34.8

19.8

24.5

21.2

14.8

13.2

1.8.8

~5.5

10.6

~7*~

~7.8

38.5

12.7

NOTE: tt = eample size; iV=estimated number of youths in population in thousands; ~=mean;

S = standard deviation; Sz= standard error of the mean.

27
Table 12. Skewnesscoefficients (differencebetween the 50thand 95th percentiledividedby the

differencebetween the 5th and 50th percentile)by skinfoldsite, race, sex, and age at last

birthdayof youths:United States,1966-70

Sex and age

6

7

8

9

10”

11

12

13

14

15

16

17

Male

years-------------------

years-------------------

years-------------------

veals-------------------

years------------------

years------------------

years------------------

years------------------

years------------------

years------------------

years------------------

years------------------

Female

6 years-------------------

7 years-------------------

8 years-------------------

9 years-------------------

10 years------------------

11 years------------------

12 years------------------

13 years------------------

14 years------------------

15 years------------------

16 years------------------

17 years------------------

Triceps

skinfold

White

1.67

2.17

3.00

3.00

2.63

2.67

2.98

2.85

3.45

3.88

3.87

3.62

1.50

2.29

1.80

2.44

1.83

2.00

2.21

2.07

1.81

1.93

1.66

1.71

1.33

2.00

2.60

3.00

2.00

3.67

4.49

4.97

4.58

3.31

2.32

5.17

3.50

3.40

4.00

2.50

2.80

2.50

3.27

4.54

1.73

2.29

3.00

1.97

Wbscapular

skinfold

Jhite

3.00

2.33

4.66

6.67

6.67

5.75

7.30

7.55

5.93

6.07

6.15

5.37

3.67

7.00

5.00

6.50

7.00

4.33

5.04

4.74

3.90

4.38

4.12

3.93

Vegro

2.50

3.00

1.00

1.50

4.66

6.00

8.12

5.35

4.10

2.69

1.70

5.45

2.00

2.50

8.00

4.00

3.00

4.33

4.31

6.30

4.21

3.81

5.06

3.34

fidsxillary

skinfold

tiite

2.00

4.00

6.00

11.00

IS. 00

6.50

8.23

7.74

7.52

6.92

6.09

7.63

6.00

4.33

5.00

5.00

4.67

5.20

5.60

;.;;

4:52

4.00

4.16

!Tegro

2.00

1.33

2.00

3.00

6.00

9.00

7.75

6.23

3.34

3.78

1.88

LO.33

3.00

4.00

4.67

3.50

5.50

5.50

4.54

5.29

3.07

4.86

4.10

2.97

Suprailiac

skinfold

Jhite

4.3(i

5.18

4.81

4.83

4.29

4.59

;.;:

2:17

2.37

2.08

2.39

legro

6.4;

7.93

6.03

6.84

3.12

6.88

-

2.8;

;.::

2:14

3.51

2.38

Medial calf

skinfold

Jhi.te

2.67

2.82

2.99

2.84

3.14

3.05

-

2.3;

1.92

1.69

1.87

1.64

1.78

Iegro

3.0;

4.99

4.64

4.10

2.23

4.29

2.90

3.34

1.70

2.17

3.61

1.69

28
Table 13. Sample size and correlation coefficients far all p;;~~& pairs of skinfolds of youths by race and sex: United States,

Sate and sex

says kTricepsCalf

Skinfold pair

3ubscapUlarnidaxillary

.9114

.9100

.9017

.9123

3ubscapularsuprailiac

.8371

fdaxillarysuprailiac

.8523

:ubscapularCalf

!Iidaxillarycalf

.7437

Suprailiaccalf

.7256

.7920

.6S50

.7127

Tricepsmbscapular

.S063

rricepsnidaxillary

.8002

rricepssuprailiac

——

.7790

+

I

Totall

Both sexes----- .7351

.7497

.6890

.7346

.7454

.6956

.7794

.8065

.7224

Male---------------

F~ale ........-...-

3,513 .8745

3,172 .8149

.7537

.7004

.7388

.7454

.7005

.7824

.S088

.7s35

.8068

.7951

.7797

.Soos

.S3S0

.7540

.7724

.8691

.8296

.5349

.8709

.S527

.8483

White

Both sexes-----

+

Male ---------------

Female-------------

3,020 I

.S701

2,65o .S185

.7817

.6802

.7883

.s077

.7893

.8179

.7910

.7s79

.7960

.8336

.7545

.8059

.9081

.9054

.9138

.8703

.8289

.8666

.8683

.8524

.8812

.8901

.8627

Negro

Both sexes----- -1- 982 .8584

Male---------------

Female-------------

.8135

.7180

.8301

.72S0

.8173

.7816

.8144

.7404

.8464

.7490

.9309

.8904

.8829

.8426

lIncludes data for “other races,” which are not shc.wnseparately.

29
Table 14. Sample size and correlation coefficients for all possible pairs of skinfolds of youths by race, sax, and age at last

birthday: United States, 1966-70

Race, sax, and.ase

12

;2

15

16

17

12

H

15

16

17

12

13

14

::

17

12

13

14

15

16

17

12

13

14

15

U

12

13

14

!:

17

T~AL1

~

years-----------

years-----------

years-----------

years-----------

years-----------

years-----------

ue

years-----------

years-----------

years-----------

years-------7---

years-----------

years-----------

WIWTE

Male —

years-----------

years-----------

years-----------

years-----------

years-----------

years-----------

Female

years-----------

years-----------

years-----------

years-----------

years-----------

years-----------

~(1

Hale —

years-----------

years-----------

years-----------

years-----------

years-----------

years-----------

Famale

years-----------

years-----------

years-----------

years-----------

years-----------

years-----------

636

620

611

609

551

4s5

532

579

579

495

529

458

535

537

521

522

491

413

446

487

478

418

:;;

99

i?

:;

69

82

1%

i;

70

:ricepscalf

.S7S6

.8801

.8666

.8874

.8722

.8502

.S286

.8568

.7848

:;;;:

.7556

.8752

.8716

.8605

.8885

.8703

.8400

.8437

.8449

.8170

.8189

.7804

.7544

.S725

.9224

.8992

.S089

.8887

.9104

.7164

.9081

.6402

.8201

.8516

.7138

Skinfold pair

‘==E=I==

.7651

.7847

.7598

.7941

.7288

.7939

.7422

.7479

.6218

.6942

.6623

.6142

.7581

;;:;;

.7992

.7300

.782S

.7485

.7400

.6370

.7073

.6489

.6348

.S198

.8346

.8757

.6929

.7807

.8979

.7419

,s431

.5766

.6693

.8118

.6893

.7836

.7757

.7740

.7487

.7510

.7992

.8479

.8152

.7966

.83o6

.7527

.7959

.7492

.7539

.6608

.6965

.6534

.5758

.8394

.8092

;;;7;

.7467

.7810

.7568

.7448

.6592

.6895

.6403

.5756

.8419

.8533

.8910

.7147

.7971

.8706

.7039

;::::

.7355

.7551

.6689

i’ricepssubscapular

.8258

.8511

.S206

.8345

.8232

.8260

.8125

.8161

.7189

.7874

.7723

.7613

.8228

;:3;;

.8413

.8241

.8285

.8155

.8152

.7539

.797s

.7636

.7577

.8978

.9124

.S630

.6638

.8346

.8380

.8242

.8604

.5736

.7353

.8566

.s509

‘riceps-

!idaxillary

.8285

.8177

.8328

.7714

.8271

.8073

.8117

.8112

.7406

.8002

.7555

.7398

.8244

.Slol

.8325

.7709

.8250

.8001

.8256

.8097

.7786

.s053

.7511

.7404

.S984

.9167

.8516

.7106

.8540

.8503

.7296

.8357

.5632

.7s73

.7958

.7S20

rricepssuprailiac

.8652

.8780

.8636

.8714

.8126

.8167

.8015

.7993

.7261

.7725

.7387

.6916

.8575

.8761

.8568

.8748

.8106

.8118

.8111

.7869

.7538

.7614

.7375

.6901

.9019

.8868

.8991

.7499

.8120

.8436

.7481

.8464

.5976

.8352

.7662

.7033

hll.l=ap

nidaxil

lary

.9332

.9100

.9156

.8946

.9017

.9226

.9123

.9074

.8926

.9117

.8849

.8953

.9316

.9054

.9171

.8952

;;;;;

.9198

.9025

.8937

.9134

.9008

.8972

.9282

.9673.

.9407

.8747

.8643

.9458

.8581

.9397

.8934

.9096

.8576

.9039

T

Subscap- Mfdaxilular- larystipra- suprailiac iliac

.8533

.8840

.8794

.8765

.8575

.8701

.8459

.8654

.8198

.8281

.8286

.7978

.8513

.8833

.8797

.s779

.8608

.8814

.8508

::;;:

.8259

.8283

.7898

.9019

.9023

.9024

.8723

.8212

.8873

.8270

.9039

.8001

.8549

.8369

.8475

.8857

.8646

.8879

.8322

.8778

.8894

.853o

.8901

.8555

.8558

.8377

.8209

.8807

.8590

.8900

.8312

.8770

.8919

lIncludes data for ‘)otherraces,” which are not shown separately.

30
Table 15. Rankings of correlation coefficients for all possible pairs of skinfolds of youehs with each race, sex, and age group:

United States. 1966-70

Race, sex, and age

TOTAL1

~

12 years-----------

13 years-----------

14 year8-----------

15 years-----------

16 years-----------

17 years-----------

F12 years-----------

13 years-----------

14 year5-----------

15 year9-----------

16 year8-----------

17 yeax8-----------

WHJH

*

12 year8-----------

13 years-----------

14 yeara-----------

15 ycmx+----------

16 years-----------

17 years-----------

l?emale

12 yettrs-----------

13 years-----------

14 years-----------

15 years-----------

16 years-----------

17 years-----------

NEGRO

~

12 yeaz9-----------

13 years-----------

14 years-----------

15 years-----------

16 years-----------

17 years-----------

Female

12 years-----------

13 years-----------

14 years-----------

15 years -----------

16 years -----------

17 ycare----r ------

532

579

579

495

529

458

446

487

478

418

636

387

Skinfold pair

Cricepscalf

8

8

;

8

7

7

7

7

;

6

8

7

;

8

7

7

;

7

7

6

4

8

s

7

10

8

2

8

6

6

7

5

3:;IJ=:P -

calf

1

2

i

i

1

1

1

1

3

2

1

2

1

3

1

2

1

1

1

2

3

2

2

:

2

1

7

:

3

1

5

2

iidaxillarycalf

2

1

2

1

2

3

3

2

2

3

2

3

2

1

2

1

3

3

3

:

3

1

3

1

3

6

:

5

4

:

2

3

3

SuprailiacCalf!riceps-

;ubscapular

l-icepsxLdaxillary‘ricepssuprailiac

;:llyr:p-

]idaxilIary

;:;:r:p -

suprailiac

[idaxillarysuprailiac

9

6

9

:

9

9

9

9

9

9

9

9

;

;

9

;

9

9

9

9

10

9

:

9

9

;

9

9

10

9

1

Includes data for “other races,

,,which ~re not shown separately.

31
Table 16. Triceps skinfold of youths by geographicregion, sex,

meted populationsize,mean, standarddeviation,standarderror

States,1966-70

Geographicregion,

sex, and age

12

13

ii

16

17

12

i:

15

16

17

12

13

14

15

16

17

12

13

14

15

i;

$:

14

:;

17

12

13

14

15

16

17

12

13

14

15

16

17

12

13

#

17

NORTHEAST

M&e

years---------------

years---------------

years---------------

years---------------

years---------------

years---------------

Female

years---------------

years---------------

years---------------

years---------------

years---------------

years---------------

MIDWEST

Male

years---------------

years---------------

years---------------

years---------------

years---------------

years---------------

Female

years---------------

years---------------

years---------------

years---------------

years---------------

years---------------

SOUTH

Male

years---------------

years---------------

years---------------

years---------------

years---------------

years---------------

Female

years---------------

years---------------

years---------------

years---------------

years---------------

years---------------

WEST

U

years---------------

years---------------

years---------------

years---------------

years---------------

years---------------

Female

years---------------

years---------------

years---------------

years---------------

years---------------

years---------------

Jn

173

162

156

137

124

11s

135

145

139

121

125

106

167

163

162

162

152

116

150

157

148

10s

140

132

149

149

149

M;

130

128

142

161

138

126

117

154

152

150

151

130

125

134

13s

138

135

144

113

N

474

475

466

393

373

364

469

430

411

398

390

388

569

582

538

571

528

474

586

588

530

483

500

536

446

459

454

460

481

430

430

435

482

474

386

410

543

490

489

475

451

496

485

493

478

493

.511

410

and age at last birthday:sample size, estiof the mean, and selectedpercentiles,United

Percentile

x s s%

5th 10th 25th 50th 75th 90th 95th

In millimeters

11.5

10.8

10.O

8.9

1:::

13.5

13.8

15.1

15.3

17.0

16.9

11.1

10.7

10.2

9.3

9.2

8.6

13.7

14.0

15.6

16.4

17.4

16.8

10.0

10.0

8.3

8.7

8.7

8.7

13.1

13.2

14.6

16.7

15.8

15.9

10.0

10.3

9.3

::!

8.4

11.0

13.1

14.0

14.9

15.8

16.1

5.73

6.41

6.03

5.29

5.48

6.87

5.95

6.18

5.63

6.97

6.14

6.39

6.58

5.91

5,68

5.39

5.13

5.41

5.76

6.22

6.37

6.66

6.90

6.24

5.31

5.63

4.40

5.34

4.81

5.09

6.53

6.51

6.72

6.81

8.20

5.58

5.32

5.35

5.86

4.31

4.23

4.16

4.54

5.27

5.51

5.80

6.26

6.63

0.65

0.38

0.60

0.44

0.59

0.57

0.75

0.54

0.54

0.43

0.52

0.54

0.54

0.66

0.46

0.60

0.59

0.53

0.58

0.74

0.52

0.90

0.88

1.06

0.45

0.47

0.50

0.46

0.38

0.40

0.46

0.41

0.37

0.78

1.28

0.32

0.47

0.44

0.64

0.51

0.50

0.52

0.58

0.57

0.71

0.70

0.41

1.29

::;

4.2

4.3

4.5

4.5

:::

7.5

7.2

7.6

7.9

5.1

:::

4.5

4.4

3.6

Z::

;:;

8.5

9.1

4.4

4.1

M

u

6.0

‘$;

7:5

8.1

5.0

::!

4.3

‘::;

5.6

6.5

M

7.5

7.6

6.2

;:;

4.8

5.1

5.1

;::

9.0

8.3

1::;

H

5.2

H

4.3

7.8

;:!?

1:::

10.5

N

4.6

4.4

t::

6.7

;:?

9.4

9.1

9.4

5.4

::$

:::

4.5

6.4

7.5

7.8

H

8.8

;::

6.4

6.0

6.0

6.4

9.2

lvi

11.3

12.9

12.6

::;

6.5

6.0

6.1

5.4

9.5

1?:2

11.9

12.7

12.2

6.5

6.3

5.6

5.4

5.6

5.4

S.6

1:::

11.6

10.6

12.1

6.6

;:;

:::

5.4

8.1

9.7

1?::

11.6

10.6

10.3

9.5

8.4

7.3

:::

12.5

12.7

15.2

14.2

17.3

16.4

9.6

8.8

8.8

7.9

7.6

7.2

12.6

13.1

14.4

15.2

15.9

16.2

9.0

8.8

7.2

7.3

7.5

7.2

:;.:

13:6

15.9

13.5

15.7

8.7

9.2

;::

7.2

7.1

10.5

12.3

12.9

14.4

15.4

15.3

14.1

13.4

12.6

10.7

12.2

12.4

16.8

18.1

18.3

18.4

21.1

22.0

13.6

14.1

13.2

10.8

11.9

10.3

16.9

17.6

20.0

20.6

21.8

20.5

13.1

11.7

1:::

11.1

11.1

17.1

16.7

18.3

20.8

19.5

18.7

12.2

12.8

11.6

10.7

10.2

11.1

13.5

15.7

18.5

18.4

19.7

21.0

20.7

20.6

18.2

16.3

17.2

21.7

23.1

23.4

23.3

23.8

24.8

24.7

20.6

19.3

17.4

16.5

16.5

15.4

23.6

24.4

25.9

26.5

27.3

27.2

17.9

18.5

;$;

15:2

14.4

21.6

23.2

22.7

25.8

25.4

23.3

18.5

19.1

17.4

14.9

14.7

15.3

17.4

20.5

22.6

23.1

24.5

25.4

25.3

25.1

22.4

21.4

23.0

28.2

25.3

25.6

25.7

30.2

29.0

27.4

24.8

22.8

23.4

22.4

20.4

19.7

25.6

25.5

28.6

29.5

31.3

29.8

22.3

22.5

19.4

19.8

19.3

21.3

25.8

;:.:

31:7

31..3

26.6

21.5

21.9

21.6

19.4

1s.3

16.8

20.7

25.u

23.9

25.6

26.4

27.7

NOTE: ?&- sample size; ~= estimatednumber of youths in populationin thousands;~= mean; S= standard

deviation; SZ= standarderror of the mean.
Table 17. Subscapularskinfoldof youths by geographicregion, sex, and age at last birthday: sample size,

esti.metedpopulationsize, mean, standarddeviation,standarderror of the mean

United States, 1966-70

, and selectedpercentiles,

Geographicregion,

sex, and age

12

:;

15

16

17

NORTHSAST

Male

years--------------

years--------------

years--------------

years--------------

years--------------

years--------------

Female

years--------------

years--------------

years--------------

years--------------

years--------------

years--------------

M20WEST

Male

years--------------

years--------------

years--------------

years--------------

years--------------

years--------------

Female

years--------------

yeare--------------

years--------------

y6ars--------------

years--------------

years--------------

SOUTH

Male

years--------------

years--------------

years--------------

years--------------

years--------------

years--------------

.—Female

years--------------

t: vears .- --------------

14 ~ears--------------

15 years --------------

16 years--------------

17 years--------------

WEST

Male

12 years ------------

13 years --------------

14 years --------------

15 years --------------

16 years--------------

17 years--------------

Female

12 years--------------

13 years --------------

14 years--------------

15 years --------------

16 years--------------

17 years--------------

n

173

162

156

137

124

117

135

145

139

120

125

106

167

163

162

162

152

116

149

157

14s

108

140

132

149

149

150

163

149

129

128

142

161

138

126

118

154

152

150

151

131

125

134

138

138

135

145

113

N

474

475

466

393

373

361

469

430

411

394

390

388

569

582

538

571

528

474

583

588

530

483

500

536

446

459

456

460

481

427

430

435

482

:;$

412

543

490

489

475

453

496

485

493

478

493

513

410

~Percentile

x s Sz

5th 10th 25th 50th 75th 90th 95th

8.1

8.4

8.3

8.6

1:::

10.4

11.2

11.5

12.4

13,3

13.1

/$:

i::

;:;

10.2

11.2

12.2

12.6

13.6

13.6

6.6

7.8

;::

8.4

8.8

10.3

10.6

11.6

13.2

12.6

12.7

7.0

8.0

S.5

8.2

;::

;:’$

10,8

11.5

12.7

13.5

5.71

6.49

6.lC

5.7?

5.12

5.7t

5.82

6.75

6.12

6.97

6.48

6.88

5.80

6.29

4.96

6.06

4.89

5.58

6.16

7.28

6.79

7.56

7.53

8.12

:.;:

4:78

5.00

5.19

4.55

7.91

6.S4

7.94

8.0S

9.14

7.34

5.45

5.s7

6.46

4.62

4.47

4.67

4.42

6.28

5.64

6.03

6.98

8.25

0.45

0.37

0.60

0.34

0.39

0.45

0.34

0.49

0.95

0.72

0.77

0.53

0.32

0.53

0.50

0.42

0.59

0.60

0.71

0.83

0.70

0.71

0.61

1.27

0.36

0.33

0.51

0,30

0.42

0.38

0.60

0.47

0.23

0.56

1.12

0.38

0.79

0.57

0.67

0,46

0.37

0.66

0.51

0.63

0.50

0.68

:.;:

4.1

4.1

2::

5.C

5.4

4.8

5.1

5.6

6.0

H

2::

4.4

4.6

2:;

4.5

::!

:::

6.2

;::

4:4

5.0

5.0

4.4

4.9

5.1

5.8

5.5

5.8

:::

3.9

:::

5.3

4.3

4.7

H

6.2

6.4

In millimeters

::i

4.(

5.(

5’

b:i

5.:

5.5

6.:

6.!

7.:

7.i

::;

4.9

5.1

:;;

H

6.7

6.5

:::

4.2

4.3

:::

5.2

5.3

4.8

5.4

5.6

6.5

:::

4.0

4.2

4.4

H

5.8

4.8

2:?

6.2

6.8

7.0

5.1

;::

5.8

6.1

7.0

6.2

7.0

H

9.0

8.4

4.8

5.2

5.4

5.7

6.3

6.4

:::

8.0

::;

8.1

4.7

::;

5.5

5.9

6.4

6.1

6.7

:::

;::

4.5

4.8

5.3

~:;

.

5.7

6.2

7.2

7.7

7.8

7.9

6.1

:::

b.!

;:;

8.7

:::

10.1

12.2

11.5

5.7

6.2

6.6

6,.8

7.3

7.7

7.9

1:::

10.4

10.8

11.4

5.6

6.0

;::

7.3

7.6

7.7

:::

10.4

1?::

5.5

5.9

6.3

7.2.

%;

6.9

;:;

10.2

10.9

11.1

9.1

8.4

;:;

9.:

11.1

13.3

13.5

13.7

15.2

16.6

16.6

:::

%:

1:::

12.7

13.2

14.9

15.4

15.9

18.5

6.8

7.9

7.7

;::

10.3

11.3

12.2

13.6

15.3

14.8

15,1

::;

9.2

::;

10.5

1::;

13.5

14.4

14.9

17.5

14.8

17.3

15.1

15.4

15.5

18.(

19.1

21.2

19.5

21.8

22.3

22.8

15.9

13.4

13.5

15.4

15.4

15.9

21.1

22.9

23.2

24.8

25.4

24.4

10.6

16.4

13.7

12.0

13.2

14.3

20.8

20.8

20.8

27.3

24.6

21.1

11.6

16.1

14.7

12.6

13.0

17.4

14.2

19.2

17.6

20.1

24.6

23.6

21.6

21.9

22.6

23.9

21.2

25.0

23.1

26.9

25.7

29.3

25.9

31.6

21.9

20.2

16.8

21.5

20.3

19.6

24.3

27.7

29.1

30.2

31.5

29.7

18.1

24.4

18.3

16.5

20.7

21.0

27.8

25.4

26.5

31.0

32.3

28.6

17.7

21.8

25.5

18.0

17.0

20.5

17.7

23.2

20.9

24.7

29.2

35.1

NOTE: ?l= sample size; ~= estimatednumber of youths in populationin thousands;z = mean; s = standard

deviation; Si= standarderror of the mean.

33
Table 18. Midexillary skinfold of youths by geographic region, sex, and age at last birthday: sample size,

estimated population size, mean, standard deviation, standard error of the me-, ,and selected percentiles,

United States, 1966-70

Geographicregion,

sex, and age

NORTHEAST

Male

12 years---------------

13 years ---------------

M years ---------------

15 years---------------

16 years---------------

17 years---------------

Female

12 years---------------

13 years ---------------

14 years---------------

15

16

17

12

13

14

15

16

17

12

14

15

16

17

12

13

14

15

16

17

12

~

16

17

12

13

14

15

16

17

years---------------

years---------------

years---------------

MIDWEST

~

years---------------

years---------------

years ---------------

years ---------------

years ---------------

years ---------------

Female

years ---------------

years ---------------

years ---------------

years ---------------

years ---------------

years ---------------

SOUTH

Male

years---------------

years---------------

years---------------

years---------------

years---------------

years---------------

Female

years---------------

years---------------

years---------------

years---------------

years---------------

years---------------

wi

Male

years---------------

ykars---------------

years---------------

years---------------

years ---------------

years ---------------

Female

years---------------

years---------------

years---------------

years---------------

years---------------

years---------------

B

173

162

156

137

124

117

134

145

139

120

125

106

167

163

162

162

152

116

150

1.57

148

108

140

132

149

149

150

163

149

130

128

142

161

139

126

118

154

152

149

151

131

125

134

138

138

135

145

113

Iv

474

475

466

393

373

361

466

430

411

394

390

388

569

582

539

571

529

474

586

588

530

483

500

536

446

459

456

460

481

430

430

435

482

476

386

412

543

:;;

475

453

496

485

493

478

493

513

410

Percentile

x .!? Sz

5th 10th 25th 50th 75th 90th 95th

7.1

7.2

7.2

7.4

7.0

8.6

9.3

1::?

10.4

11.6

10.7

6.5

6.5

6.5

7.2

7.3

7.4

9.3

1?::

11.2

12.2

11.6

5.7

6.2

6.1

6.4

6.7

7.2

8.5

9.0

1:::

10.0

10.0

5.9

6.6

:::

6.3

7.4

7.2

8.5

1;::

10.9

11.3

;.;;

7:00

6.27

5.10

6.24

5.54

6.24

;.::

::;;

.

4.91

5.39

5.03

5.90

5.39

5.88

5.90

:.::

6:99

8.08

7.69

4.45

4.96

4.64

4.84

4.40

5.38

7.34

6.20

6.66

7.96

6.75

5.55

4.85

5.10

5.92

5.06

4.19

5.32

;.::

5:61

6.21

6.52

7.49

0.54

0.33

0.88

0.41

0.37

0.59

0.27

0.35

0.81

0.41

0.53

0.60

0.21

0.39

0.43

0.46

0.65

0.56

0.58

0.78

0.57

0.75

:.;:

.

0.34

0.31

0.45

0.28

0.31

0.52

0.53

0.43

0.17

0.79

0.58

0.27

0.62

0.44

0.58

0.56

0.49

0.86

0.43

0.44

0.52

0.75

0.76

1.34

3.2

3.2

3.3

3.3

u

4.1

4.1

4.4

4.6

::;

3.0

3.2

3.3

3.6

3.5

3.4

2:?

2:;

2:;

3.1

::?

$:

.

::?

$;

4:5

:::

3.1

3.4

3.3

4.0

3.4

3.5

4.3

4.3

4.9

4.7

In millimeters

3.4

3.5

3.6

3.6

::;

4.3

4.8

;.;

6:2

5.9

3.2

3.4

:::

4.0

3.8

4.5

4.5

5.9

5.4

5.7

5.3

3.2

3.3

3.3

3.6

i::

:::

4.4

2::

5.2

3.1

3.3

3.3

3.8

;::

::;

4.8

4.8

5.4

5.3

4.1

4.2

:::

4.6

4.8

5.2

6.1

6.5

6.3

7.8

7.1

::!

4.3

4.5

4.7

4.6

5.5

5.7

6.8

6.6

7.1

6.5

;:;

4.1

:.;

4:5

4.7

5.5

;.;

6:2

6.6

3.6

:::

4.4

4.3

4.6

4.7

:.;

6:3

6.7

6,4

5.2

5.2

5.2

;:;

6.4

7.6

7.8

::;

10.4

9.2

4.8

;.:

5:4

5.6

5.7

7.1

;:2

8.6

9.6

9.0

4.6

4.8

4.7

5.1

5.6

5.4

6.4

6.9

7.6

8.4

7.8

8.8

4.5

4.9

4.9

5.4

5.4

5.6

5.9

7.1

8.1

8.5

9.1

8.4

7;6

:::

7.6

1;:;

12.4

12.1

12.4

12.2

14.4

12.9

7.1

7.0

7.0

7.5

7.6,

7.6

12.1

11.9

13.6

13.8

14,5

15.5

6;1

6,,3

::!

7:6

1%;

12.1

15.2

u. 9

11.8

6.2

;.:

7:4

7.0

7.5

1:::

12.2

12.6

12.5

14.9

15.9

15.2

14.8

16.3

13.5

17.5

17.1

18.5

18.4

20.5

18.1

16.9

15.1

10.8

11.4

13.7

13.5

13.5

19.3

19.8

22.2

20.9

28.3

22.1

10.4

13.4

11.7

11.0

11.7

13.7

23.1

18.0

17.8

24.4

18.8

15.8

10.9

13.3

14.6

12.0

10.6

15.7

14.0

14.6

18.8

19.4

20.8

22.1

21.5

20.4

25.1

22.9

21.2

22.7

19.7

27.1

21.7

26.7

23.1

21.8

19.8

18.3

17.4

20.5

19.5

21.5

24.3

23.6

25.0

27.5

31.1

24.9

17.2

18.7

14.7

16.7

15.6

18.8

25.5

23.0

23.8

29.6

25,1

24.2

18.1

19.7

22.2

17.2

14.1

22.6

17.9

21.2

21.1

25.2

25.4

27,0

NOTE : n = sample size; N= estimated number of youths in population in thousands; ~- mean; S = standard

deviation; SZ - standard error of the mean.

34
Table 19. Suprailiacskinfoldof youths by geographicregion, sex, and age at last birthday:sample size,

estimatedpopulationsize, mean, standarddeviation,standarderror of the mean, and selectedpercentiles,

United States, 1966-70

Geographicregion,

sex, and age

NORTHSAST

Male

years---------------

years---------------

years---------------

years---------------

years---------------

years---------------

Female

years---------------

years---------------

years---------------

years---------------

years---------------

years---------------

MIDWRST

Male

years---------------

years---------------

years---------------

years---------------

years---------------

years---------------

Female

years---------------

years---------------

yeare---------------

years---------------

years---------------

years---------------

SOUTH

Male

years---------------

years---------------

years---------------

years---------------

years-------u-------

years---------------

Female

years---------------

years---------------

years---------------

years---------------

years---------------

years---------------

WEST

Male

years---------------

years---------------

years---------------

years---------------

years---------------

years---------------

Female

12 years---------------

13 years---------------

14 years---------------

15 years---------------

16 years---------------

17 years---------------

n

173

162

156

137

124

117

135

145

139

120

125

106

167

163

162

162

152

116

149

157

148

108

140

131

149

149

150

::;

130

127

142

161

139

126

118

151

152

150

151

131

124

134

138

138

135

145

113

N

474

475

466

39~

373

361

469

430

411

394

390

388

569

582

538

571

528

474

582

588

530

483

500

532

446

459

456

460

479

430

426

435

482

;::

412

538

490

489

475

453

492

485

493

478

493

513

410

I

Xs

12.9

12.8

12.0

12.5

13.1

15.6

15.0

15.8

15.6

15.7

16.5

16.2

12.3

11.6

12.4

13.1

13.2

13.4

14.9

14.6

16.0

16.2

16.7

15.6

10.5

11.7

11.0

11.3

12.0

12.7

13.6

14.2

14.9

16.7

15.2

15.3

11.5

12.7

12.8

13.1

12.2

14.0

12.0

14.3

15.3

16.6

16.2

16.7

9.53

10.26

9.92

9.19

9.43

10.87

8.67

8.58

7.00

7.24

7.10

7.73

9.77

8.78

9.12

9.64

8.75

9.13

8.49

8.11

7.50

8.63

8.40

8.61

8.09

9.48

8.60

8.79

8.48

9.28

8.68

8.65

8.66

9.16

9.04

8.69

8.75

9.47

9.78

8.20

7.35

9.97

7.15

7,53

7.63

8.32

7.77

9.34

I

I

Percentile

SF

5th 10th 2!ith 50th 75th 90th

0.87

0.45

0.98

0.47

0.56

0.61

0.56

0.52

1.11

0.59

0.52

0.72

0.49

0.63

0.89

0.62

0.98

0.56

0.94

0.72

0.79

1.17

0.97

1.16

0.59

0.85

0.78

0.73

0.93

0.99

0.66

0.71

0.63

0.94

1.30

1.04

0.77

0.79

0.73

0.89

0.81

1.71

0.86

0.69

0.72

0.90

0.86

1.76

,

:::

4.L

5.(

5.>

5.(

4.5

:::

6.4

:::

H

4.3

::;

4.7

5,4

5.1

:::

6.5

5.6

3.6

:::

4.3

4.7

4.7

4.6

:::

6.6

:::

4.1

:.;

4:8

5.1

5.3

4.5

5.8

6.1

5.7

z::

In millimeters

4.6

4.9

4.8

5.5

R

5.8

6.8

7.8

;::

8.4

:::

5.2

::;

5.4

6.2

6.1

7.8

7.4

:::

4.3

4.4

4.5

4.7

5.4

5.4

u

6.4

7.6

7.0

7.8

4.5

4.6

4.6

z::

5.8

5.2

2::

;:;

7.5

6.1

2:;

6.8

;:;

:::

10.6

10.8

11.4

10.8

H

6.5

6.8

:::

;::

10.5

1::;

9.5

5.6

5.8

::;

6.9

6.8

n

8.6

10.3

1:::

;::

6.4

:::

7.4

;:;

10.3

10.6

11.3

9.7

10.1

8.7

:::

1::2

13.2

14.6

15.3

14.9

15.8

14.5

7.8

;:;

1;:;

10.3

13.2

13.2

14.8

14.5

15.3

13.8

::2

R

::;

12.0

12.3

13.3

14.0

12.5

13.3

;:?

1::2

10.3

10.8

10.7

12.7

13.3

15.4

14.5

13.6

17.6

15.3

14.0

14.6

16.1

20.8

20.3

19.4

19.6

20.5

20.4

20.6

16.2

14.8

14.9

16.2

17.4

17.8

20.4

18.5

20.6

20.6

20.7

21.4

12.6

14.2

12.4

12.4

15.3

16.3

18.3

19.1

19.3

22.8

19.1

18.6

15.0

18.1

15.8

15.9

15.4

16.8

14.6

18.6

21.1

21.8

20.2

22.7

27.3

30.5

25.5

27.6

27.8

34.4

27.6

27.7

25.6

25.2

27.2

26.6

27.7

24.8

26.1

26.8

25.5

27.5

25.8

26.8

27.3

30.0

30.5

28.4

20.8

26.2

26.2

25.4

24.0

28.5

25.4

27.0

27.0

30.3

27.4

24.3

26.5

27.7

28.7

25.9

24.4

30.5

22.3

24.5

26.1

28.0

28.3

30.6

95th

36.0

35.3

36.2

36.6

33.7

38.6

31.3

36.2

30.4

31.5

30.3

33.3

32.4

30.7

31.8

35.6

33.2

29.8

32.5

30.4

31.4

35.0

34.1

31.4

28.2

33.8

30.4

30.2

32.4

34.3

37.0

32.4

35.0

35.4

35.5

31.4

31.9

34.4

36.1

30.4

28.8

38.6

27.0

30.2

28.9

31.2

31.7

33.2

FTom: n= sample size; iV= estimatednumber of youths in populationin thousands; ~= mean; s= standard

deviation; Si = standarderror of the mean.

35
Table 20. Medial calf skinfoldof youths by geographicregion, sex, and age at last birthday:sample size,

estimatedpopulationsize, mean, standarddeviation,standarderror of the mean, and selectedpercentiles,

United States. 1966-70

Geographicregion, sex, and age

12

13

12

13

14

15

16

17

12

13

14

15

16

17

12

12

17

12

NORTHEAST

we

years---------------------------

years---------------------------

years---------------------------

years---------------------------

years---------------------------

years---------------------------

Female

years---------------------------

years---------------------------

years---------------------------

years---------------------------

years---------------------------

years---------------------------

MIDNEST

&

years---------------------------

years---------------------------

years---------------------------

years---------------------------

years---------------------------

years---------------------------

Female

years---------------------------

years---------------------------

years---------------------------

years---------------------------

years---------------------------

years---------------------------

fim

~

years---------------------------

years---------------------------

years---------------------------

years---------------------------

years---------------------------

years---------------------------

Female

years---------------------------

yeara---------------------------

years---------------------------

yeara----.--------------~-------

years---------------------------

years---------------------------

WEST

~

years---------------------------

years---------------------------

years---------------------------

yeara---------------------------

years---------------------------

years---------------------------

Female

years---------------------------

years---------------------------

years---------------------------

years---------------------------

years---------------------------

years------------------------:--

n

172

159

155

137

123

118

131

145

139

119

124

104

166

162

162

162

151

116

147

156

144

107

139

131

147

147

148

161

149

129

124

142

158

138

124

114

154

152

147

149

130

124

134

136

138

133

143

111

N

471

466

463

393

370

364

457

430

411

392

386

375

565

579

538

571

526

474

576

584

515

478

497

532

441

444

451

454

481

427

415

435

471

$;;

401

543

490

481

469

451

493

485

487

:;:

506

402

12.9

13.0

12.4

11.3

10.8

11.5

15.9

17.2

18.4

18.3

20.1

19.7

12.5

12.2

11.9

11.0

10.2

9.0

16.2

17.0

18.7

19.1

19.7

20.4

11.2

11.7

J:;

J:;

15.0

16.4

17.2

19.5

18.1

19.0

11.4

12.2

11.0

10.1

9.3

9.4

14.0

15.9

16.9

17.8

18.3

19.3

6.50

7.79

8.55

7.08

6.05

7.30

6.78

7.05

6.77

7.14

7.06

7.69

7.49

6.79

6.58

;.;;

6:07

6.72

7.60

7.47

7.21

7.63

7.76

6.39

6.63

5.36

6.35

5.79

5.88

7.44

7.35

6.88

8.99

7.59

7.29

6.74

7.00

6.77

5.31

5.42

5.37

5.91

6.47

6.66

7.31

6.66

7.96

0.69

D.53

0.74

0.63

0.68

0.49

0.73

0.40

0.98

0.60

0.46

0.36

0.50

0.78

0.69

0.75

0.54

0.67

0.51

0.65

0.58

1.05

0.76

1.04

0.41

0.62

0.39

0.58

0.61

0.68

0.62

0.69

0.63

1.24

0.91

1.07

0.58

0.62

0.87

0.57

0.50

0.73

0.65

1.02

1.15

0.91

0.84

1.24

Percentile

5eh I10th\ 25thI50thl 75th I90th I95th

In millimeters

:::

5.5

::;

5.1

!::

10.7

10.6

11.4

11.3

5.6

6.0

H

:::

9.9

1:::

10.7

11.5

10.7

5.2

u

5.0

4.8

4.7

H

1;::

10.4

11.1

5.3

5.6

::;

4.2

4.2

8.2

7.9

1:::

11.1

11.0

8.3

8.2

6.8

7.2

::2

11.2

11.8

13.8

14.1

L5.9

L5.O

7.6

7.3

::;

6.4

5.5

11.6

L1.9

12.6

14.9

14.4

15.3

6.8

:::

6.3

6.2

6.4

10.5

11.2

12.4

13.5

12.6

13.4

,-8

7.0

8.0

6.4

H

6.0

10.2

11.6

12.4

12.7

13.8

13.5

11.7

11.2

10.7

9.7

;:;

14.4

16.2

18.3

17.3

19.4

19.0

11.1

10.8

10.5

u

7.6

14.5

15.9

17.6

18.7

19.6

19.7

10.2

10.3

8.2

8,6

8.1

8.6

13.8

15.1

16.3

17.7

17.1

18.3

-.

----

1%!

9.5

;:;

8.4

13.2

14.8

15.6

17.0

17.7

17.8

L6.6

L5.4

L5.2

13.4

13.8

15.5

L9.7

22,6

22.2

22.0

25.5

24.3

15.7

15.8

15.3

13.5

L2.6

10.7

20.6

21.5

24.1

23.6

22.9

24.5

14.8

15.7

11.5

12.4

11.6

12.1

17.9

20.5

22.0

25.0

23.5

23.3

14.6

15.6

14.1

12.6

11.7

12.6

17.3

20.1

21.2

22.3

22.5

23.7

22.4

26.4

22.1

21.2

21.1

21.7

27.4

26.3

26.8

29.2

29.8

29.0

23.6

21.7

21.5

20.3

19.4

15.0

25.5

28,2

29.5

30.2

28.6

32.4

18.8

21.6

16.8

19.3

18.7

19.3

24.3

27.5

28.0

31.6

28.4

28.2

21.3

21.8

20.3

17.7

17.8

16.5

22.1

23.8

26.8

25.9

28.2

31.3

26.6

30.7

26.8

27.3

23.6

28.8

30.5

30.2

30.7

:;.;

31:3

27.9

25.8

25.6

25.6

22.2

20.8

30.7

31.7

33.4

33.8

34.7

34.8

21.6

24.5

21.4

24.0

22.6

21.7

33.1

31.8

30.5

41.1

32.3

34.3

26.6

27.8

24.7

23.2

18.9

21.2

24.4

;J:

30:3

30.1

35.1

NOTE: ?l= sample size; N= estimatednumber of youths in populationin thousands;~= mean; S- standard

deviation S5= standarderror of the mean.

36
Table 21. Triceps skinfold of youths 12-17 years of age weighing less than 30 kilograms, by sex and ageat last birthday: sample size, estimated population sizez mean,

standard deviation, standard error of the mean, and

States, 1966-70

selected percentiles, United

—

N

—

69

15

5

44

12

5;

—

I

—

n

—

24

:

12

4

1;

—

Ill Percentile

x s i%

5th 10th 25th 50th 75th 90th 95th

Sex and age

I

Male In millimeters

4.6

*

*

5.3

*

5.5

5.3

*

*

5.6

*

5.:

6.1

*

*

7.3

*

7.i

6.6

*

*

6.8

*

6.i

2.41

*

*

1.51

*

1.6;

0.61

*

*

0.64

*

0.55

2.9

*

*

5.1

*

5.6

10.7

*

*

9.0

*

9.;

11.6

*

*

9.0

*

LO.;

years -------------

years-------------

years-------------

years-------------

years-------------

years-------------

7.7

*

*

8.4

*

8.;

Female

years-------------

years-------------

years-------------

years-------------

years-------------

years-------------

n= sample size; N=estimated number of youths in population in thousands;

.X ~“~%n; S= standard deviation; Sz = standard error of the mean.

Table 22. Triceps skinfold of youths 12-17 years of age weighing 30-34.9 kilograms, by

sex and age at last birthda

??’themean, and selected percentiles, United States, 1966-

: sample size, estimated population size, mean, standard

deviation, qtandard erroro

70

—

n

—

::

3

43

11

4

1

N

I

Zs

Percentile

S2

5th 10th 25th 50th 75th 90th 95th

Sex and age

In mil meters

2:;

8

156

32

12

5

;:?

*

8.5

8.8

*

*

1.94

2.82

*

3.99

3.71

*

*

0.24

0.72

*

0.39

1.22

*

*

-!

5.0

3.7

*

4.5

3.5

*

*

H*

5.0

5.2

*

*

R*

6.6

7.2

*

*

7.4

7.1

*

8.1

8.6

*

*

8.8

8.6

*

11.3

10.7

*

*

1?:; *

13.4

17.0

*

*

10.8

12.8

*

14.1

17.3

*

*

years----------

years----------

years----------

years----------

years----------

years----------

Female

years----------

years----------

years----------

years----------

years----------

years----------

—

n== sample size; N=estimated number of youths in population in thousands;

~ ~“%in; 8= standard deviation; Si = standard error of the mean.

37
Table 23. Triceps skinfold of youths 12-17 years of age weighing 35-39.9 kilograms,

by sex and age at last birthday: sample size, estimated population size, mean, standard deviation, standard error of the mean, and selected percentiles, ~ited states,

1966-70

N

Percentile

x s Sz

5th 10th 25th 50th 75th 90th 95th

Sex and age

U

12 years---------

13 years---------

14 years---------

15 years---------

16 years---------

17 years---------

Female

12 years ---------

13 years---------

14 years---------

15 years ---------

16 years ---------

17 years---------

In millimeters

8.2

;::

*

*

9.2

8.7

8.3

8.5

9.:

536

309

106

10

5

329

253

::

1:

2.95

2.86

0.26

0.34

0.35

*

*

2::

3.4

*

*

5.4

H

4*4

7.;

H

5.9

*

*

8.8

8.6

8.4

8.6

8.;

1;.;

7:7

*

*

11.3

10.7

10.3

10.6

9.:

12.4

12.1

9.5

*

*

12.6

11.8

11.1

12.8

14.;

14.0

13.4

9.9

*

*

14.4

12.8

12.5

16.2

*

14.0

2.38

*

*

2.88

2.81

2.60

3.55

2.4;

0.29

0.38

0.47

0.83

1.0:

n= sample size; N== estimated number of youths in population in thousands;

~~O%&; s= standard deviation; Sf= standard error of the mean.

Table 24. Triceps skinfold of youths 12-17 years of age weighing 40-44.9 kilograms,

by sex and ageatlast birthday: sample size, estimated population size, mean, standard deviation, standard error of the mean

1966-70

, and selected percentiles, United States,

N

536

337

196

58

24

3

428

342

176

174

96

93

Percentile

x s SE

5th 10th 25th 50th 75th 90th 95th

n

133

112

61

19

:

118

101

%

34

27

Sex and age

Male In millimeters

12 years-------

13 years-------

14 years-------

15 years-------

16 years -------

17 years-------

10.0

8.5

:::

6.2

*

10.7

10.2

10.3

10.4

11.6

11.1

3.64

3.32

2.98

1.78

1.02

*

3.24

3.19

3.60

3.18

3.66

2.34

0.35

0.26

0.42

0.38

0.54

*

0.28

0.44

0.60

0.47

0.89

0.51

:::

3.6

%;

*

H

6.0

5.9

6.6

7.4

2::

4.2

4.0

4.9

*

7.1

:::

6.5

7.6

7.7

::;

5.1

4.7

5.4

*

8.5

8.2

U

1::!

10.2

7.8

:::

6.6

*

.

10.6

10.2

10.2

10.7

11.4

11.1

13.1

10.8

10.3

7.6

7.2

*

13.0

12.4

12.7

12.4

13.2

12.8

14.8

13.7

12.1

8.6

7.4

*

15.8

15.3

14.9

14.5

17.3

14.8

16.4

15.4

12.6

9.0

7.4

*

16.6

16.3

:;.:

19:3

15.6

Female

12 years-------

13 years -------

14 years -------

15 years -------

16 years -------

17 years -------

_ NOTE: n= sample size; N=estimated number of youths in population in thousands;

X = mean; S-standard deviation; Sx= standard error of the mean.

38
Table 25. Triceps skinfold of youths 12-17 years,of age weighing 45-49.9 kilograms,

by sex and age atlast birthdav: sample size, estimated population size. mean. standard d~viat$on,

1966-70

standard erro~ of the mean,-and selecte~ ~ercentiles, ~ited-states,

Sex and age

Male

12 years--------

13 years--------

14 years--------

15 years--------

16 years--------

17 years--------

Female

12 years --------

13 years--------

14 years--------

15 years--------

16 years--------

17 years--------

n

L!;

86

;:

12

L06

L22

L43

91

90

76

iv

299

396

264

185

83

40

372

399

$;:

293

280

IIx s Sz

11.5

8.9

7.4

R

5.6

12.6

11.0

12.0

12.7

12.1

12*2

5.33

3.44

3.18

2.68

1.85

1.96

$:;

3:26

4.10

4.08

4.18

0.76

0.26

0.32

0.31

0.35

0.59

0.60

0.30

0.40

0.48

0.56

0.83

Percentile

5th 10th 25th 50th 75th 90th 95th

In millimeters

6.1

;:;

4.4

4.1

3.4

7.8

U

8.1

7.4

7.4

::;

5.3

5.3

4.5

4.5

9.7

1:::

9.4

9.4

9.3

10.3

8.6

R

5.4

5.6

12.4

11.0

11.9

12.5

12.2

11.8

13.8

11.0

9.2

9.2

6.8

6.6

15.8

13.3

14.7

15.3

14.5

15.4

20.6

13.2

12.9

11.1

8.2

8.6

18.2

15.7

17.0

18.7

18.0

18.5

22.4

16.6

14.4

13.0

9.5

10.0

21.0

17.2

17.6

21.1

20.9

20.1

. ~= sample size; ~= estimated number of youths in population in thousands;

~-N~’%; s=standard deviation;s%=standard error of the mean.

39
Table 26. Triceps skinfold of youths 12-17 years of age weighing 50-54.9 kilograms,

by sex and age at last birthday:samplesize, estimated population size, mean, standard deviation, standard error of the mean , and selected percentiles, United States,

1966-70

Sex and age

Male

12 years--------

13 years--------

14 years--------

15 years--------

16 years--------

17 years--------

Female

12 years--------

13 years--------

14 years--------

15 years--------

16 years --------

17 years--------

n

56

88

123

93

56

32

76

97

124

106

136

103

N

161

275

373

278

184

116

273

337

385

388

442

387

I I I

Percentile

x s Sg

5th loch 25th 50th 75th 90th 95th

In millimeters

15.0

10.2

8.1

6.8

6.6

5.9

14.3

14.3

13.7

13.7

13.3

15.3

6.06

4.89

4.25

2.36

2.61

2.03

3.99

4.47

4.92

3.62

4.32

4.85

0.92

0.36

0.30

0.25

0.42

0.50

0.61

0.41

0.36

0.44

0.33

0.54

6.4

4.8

4.2

4.3

3.9

3.1

9.3

7.8

7.4

8.4

7.9

7.8

7.4

5.4

4.5

4.6

4.2

4.0

10.2

9.4

8.4

9,5

8.6

9.7

10.3

6.6

5.5

5.5

5.0

4.7

11.5

11.1

10.2

11.4

10.6

12.2

14.8

9.2

7.4

6.6

6.3

5.8

14.2

13.9

12.9

13.7

12.8

15.2

20.2

13.5

9.6

8.3

8.1

7.4

17.0

17.0

16.8

15.9

16.2

18.5

24.3

18.1

14.0

10.4

10.7

8.4

20.8

21.1

20.4

18.9

19.5

21.8

26.0

20.5

15.5

11.2

13.2

10.2

22.5

24.2

22.7

20.6

21.3

24.2

X:”%L;

n= sample size;N=estimated number of youths in population in thousands;

S = standard deviation; Sz = standard error of the mean.

40
Table 27. Triceps skinfold of youths 12-17 years of age weighing 55-59.9 kilograms,

by sex and age at last birthday sample size, estimated population size, mean, standard deviation, standard error of the mean, and selected percentiles, United States,

1966-70

Sex and age

Male

12 years-------

13 years-------

14 years-------

15 years-------

16 years-------

17 years-------

Female

12 years-------

13 years-------

14 years-------

15 years-------

16 years -------

17 years -------

48

69

106

120

108

67

51

81

98

113

105

105

N

139

223

346

396

367

243

182

275

347

406

342

409

x s s%

Percentile

5th 10th 25th 50th 75th 90th 95th

In millimeters

16.4

12.2

8.4

7.0

6.6

6.0

17.8

16.2

15.7

15.8

16.3

16.4

6.17

6.16

4.37

3.22

2.39

1.76

5.91

4.66

4.18

4.54

4.92

4.60

0.99

0.76

0.48

0.34

0.19

0.26

0.90

0.54

0.41

0.42

0.52

0.43

6.2

5.2

4.6

4.0

3.8

4.1

9.1

8.8

10.3

9.6

8.2

9.8

7.6

5.6

5.2

4.3

4.5

4.4

10.2

10.6

10.8

10.6

10.2

10.6

12.8

7.5

6.1

5.3

5.4

5.1

13.6

13.5

12.3

13.1

13.2

12.7

16.4

11.1

7.3

6.6

6.4

5.7

18.0

16.3

15.2

15.8

16.5

16.6

22.2

17.5

10.1

8.2

7.8

7.2

23.0

19.5

19.2

18.4

20.3

19.8

24.5

20.5

15.1

10.7

10.2

8.6

25.6

22.7

21.7

22.4

23.3

22.7

26.4

22.5

18.4

12.6

11.3

10.0

28.3

25.6

22.7

24.3

25.2

25.3

= sample size; N=estimated number of youths in population in thousands;

X=NO%&;nS= standard deviation; Sf = standard error of the mean.

41
Table 28. Triceps skinfold of youths 12-17 years of age weighiqg 60-64.9 kilograms,

by sex and age at last birthday:samplesize, estimated population size, mean, standard deviation, standard error of the mean, and selected percentiles, United States,

1966-70

Sex and age

~

12 years -------

13 years-------

14 years-------

15 years-------

16 years-------

17 years-------

Female

12 years-------

13 years-------

14 years-------

15 years---=---

16 years-------

17 years-------

n

18

52

72

114

117

108

29

41

61

52

74

74

N

49

169

231

350

378

397

100

133

207

192

263

263

20.3

13.6

10.0

7.9

7.1

6.7

21.7

20,1

18.7

17.8

18.6

17.9

7.90

6.90

4.92

3.24

2.96

2.61

5.29

4.86

4.55

4.86

4.68

5.02

2.30

1.34

0.52

0.30

0.24

0.29

0.87

0.71

0.45

0.86

0.69

0.75

Percentile

5th 10th 25th 50th 75th 90th 95th

7.6

5.2

4.6

4.6

3.6

3.7

12.6

11.8

12.6

12.1

12.3

10.9

In millimeters

9.5

5.5

5.5

5.1

4.2

4.2

15.2

12.9

13.7

12.6

12.8

11.5

.2.7

7.5

7.1

5.6

5.3

5.1

,8.5

,7.1

,5.7

.4.2

4.8

,4.1

22.3

13.3

8.2

7.3

6.6

6.2

22.3

20.7

18.3

17.2

19.6

18.3

27.4

20.2

12.7

10.1

8.7

8.4

25.6

24.2

22.4

20.8

21.9

22.1

29.7

24.5

18.2

12.7

12.1

10.3

26.8

25.5

25.2

25.1

24.7

24.3

33.7

26.6

20.4

15.5

12.9

12.3

29.4

28.1

27.0

25.9

26.5

25.9

NOTE: n =sample size; N=

x

estimated number of youths in population in thousands;

= mean; S= standard deviation; SiB= standard error of the mean.

42
Table 29. Triceps skinfold of youths 12-17 years of age weighing 65-69.9 kilograms,

by sex and age at last birthda~ sample size

ard deviation,

, estimated population size, mean, standstandard error of the mean, and selected percentiles,

1966-70

United States,

Sex and age

Male

12 years -------

13 years -------

14 years -------

15 years -------

16 years -------

17 years -------

Female

12 years -------

13 years -------

14 years -------

15 years -------

16 years -------

17 years -------

n

10

23

59

83

96

91

10

27

31

27

36

35

N

30

80

188

269

327

319

34

83

100

102

145

132

24.0

14.5

12.0

9.6

9.1

7.8

24..5

22.2

21.4

19.9

19.5

17.8

T

s s.x

4.38

6.66

5.16

4.54

3.69

3.44

6.63

4.11

4.91

6.18

4.08

4.71

1.84

1.52

0.70

0.52

0.44

0.51

2.69

0.79

1.28

1.12

D.66

1.00

Percentile

5th 10th 25th 50th 75th 9Oth 95th

In millimeters

16.6

6.2

5.8

4.3

5.2

4.3

14.6

16.3

12.3

10.5

13.2

12.2

20.1

7.0

6.4

5.1

5.5

4.7

17.2

17.1

13.4

13.0

13.8

12.6

20.5

10.7

8.2

7.1

6.9

5.7

20.8

20.4

18.0

16.3

16.7

14.1

27.0

12.1

11.4

8.7

7.8

7.1

24.1

22.3

22.4

20.3

20.6

17.9

28.2

19.5

15.5

12.3

11.7

9.8

30.3

25.1

25.4

23.6

22.6

21.2

30.0

26.2

19.2

15.4

14.9

13.1

31.9

28.1

28.1

29.3

25.3

24.6

30.0

27.5

20.8

21.2

16.5

14.7

39.0

28.8

28.3

30.6

26.2

27.6

n=sample size; N= estimated number of youths in population in thousands;

~ ~O%&; s =standard deviation; S% = standard error of the mean.

43
Table 30. Triceps skinfold of youths 12-17 years of age weighing 70-74.9 kilograms,

by sex and age at last birthday:sample size

ard deviation,

, estimated population size, mean, standstandard error of the mean, and selected percentiles, United States,

1966-70

Sex and age

Male

12 years -------

13 years -------

14 years -------

15 years -------

16 years -------

17 years -------

Female

12 years -------

13 years -------

14 years -------

15 years -------

16 years -------

17 years -------

n

4

12

26

53

55

68

8

8

25

21

18

16

N

10

46

81

164

181

245

28

24

73

92

68

67

1

X.s

*

18.4

13.2

11.3

11.0

9.5

24.1

24.9

24.2

21.7

23.8

24.8

*

4.97

5.03

4.84

4.76

4.27

4.22

3.69

5.31

6.16

5.44

5.33

s%

*

1.46

1.06

0.90

0.75

0.44

1.67

1.97

1.24

1.83

1.38

1.07

Percentile

5th 10th 25th 50th 75th 9Oth 95th

In millimeters

*

11.3

6.4

6.1

5.4

4.3

17.4

18.7

17.4

7.4

15.5

17.2

*

11.6

7.2

6.5

6.3

5.0

17.7

21.0

18.8

7.9

17.2

20.0

*

15.3

9.2

8.1

7.6

6.0

22.0

21.7

21.2

19.7

20.1

21.5

*

17.3

13.4

10.2

10.1

9.6

25.3

26.9

23.5

22.8

24.4

23.6

*

22.3

17.6

15.2

13.8

12.0

28.1

28.2

27.8

25.5

28.4

27.7

*

22.9

21.1

17.8

18.0

14.7

30.0

30.0

31.6

27.9

31.3

33.1

*

26.8

22.4

20.8

19.8

16.5

30.0

30.0

32.6

29.6

34.1

39.0

n= sample size; N=estimated number of youths in population in thousands; -#$:;n; S= standard deviation; s% = standard error of the mean.

44
Table 31. Triceps skinfold of youths 12-17 years of age weighing 75-79.9 kilograms,

by sex and age at last birthday: sample size, estimated population size, mean, standard deviation, standard error of the mean, and selected percentiles, United States,

1966-70

Sex and age

Male

12 years -------

13 years-------

14 years-------

15 years -------

16 years -------

17 years-------

Female

12 years -------

13 years -------

14 years -------

15 years -------

16 years -------

17 years -------

3

12

27

21

39

51

4

6

6

11

12

8

11

30

85

58

127

182

11

21

20

36

35

37

x

*

19.2

14.3

15.8

13.0

12.0

*

22.8

25.7

29.1

26.1

27.0

Percentile

C9 $E

5th 10th 25th 50th 75th 90th 95th

In millimeters

*

5.21

6.59

7.71

6.26

4.71

*

4.08

5.03

4.38

4.57

7.15

*

1.91

1.97

1.51

1.32

0.56

*

2.80

2.56

1.58

2.08

4.72

*

12.8

7.4

8.1

5.4

5.6

*

13.4

16.3

21.8

19.5

15.4

*

13.1

8.2

9.0

5.9

7.0

*

13.9

16.6

22.4

20,0

15.8

*

13.6

10.5

10.3

8.1

8.7

*

20.6

23.7

27.4

22.0

22.3

*

19.6

13.8

13.5

11.0

11.8

*

25.1

25.7

29.6

28.0

28.3

*

23.0

16.0

20.5

18.6

14.7

*

25.7

27.7

31.8

29.5

32.5

*

25.7

21.8

28.5

23.1

16.5

*

27.0

33.0

32.9

31.4

36.0

*

29.0

32.1

29.5

23.8

22.2

*

27,0

33.0

38.0

35.0

36.0

n= sample size; N-estimated number of youths in population in thousands;

~~”%m; S=stand.rd deviation; L+ = standard error of the mean.

45
Table 32. Triceps skinfold of youths 12-17 years of age weighing 80-84.9 kilograms,

by sex and age at last birthdaygsamplesize, estimated population size, mean, standard deviation, standard error of the mean, and selected percentiles,

1966-70

United States,

Sex and age

Male

12 years-------

13 years-------

14 years-------

15 years-------

16 years-------

17 years-------

Female

12 years-------

13 years-------

14 years-------

15 years-------

16 years-------

17 years-------

n

3

7

16

24

17

1

8

3

9

10

5

N

8

21

53

69

65

3

25

9

32

38

16

x

*

17.8

17.1

15.3

13.0

*

29.5

*

27.1

31.2

23.6

Percentile

s Sz

5th 10th 25th 50th 75th 90th 95th

In millimeters

*

2.87

4.27

5.56

4.53

*

7.42

*

2,08

7.30

5.98

*

1.22

1.37

1.28

1.28

*

3.19

*

0.79

2.66

3.51

*

14.6

11.4

6.4

7.1

*

17.6

*

24.4

16.8

17.1

*

14.7

11.8

6.9

7.8

*

20.1

*

24.8

23.6

17.2

*

15.6

15.3

12.2

9.8

*

20.9

*

25.6

26.0

17.6

*

18.2

17.2

14.6

12.4

*

28.6

*

27.5

31.1

23.4

*

20.5

18.5

20.6

17.4

*

36.2

*

28.6

40.0

31.0

*

23.0

26.2

23.1

19.7

*

40.0

*

30.6

40.0

31.3

.

*

23.0

28.0

25.0

20.7

*

40.0

*

32.0

40.0

31.4

_ NOTE: ?l= sample size; ~= estimated number of youths in population in thousands;

X = mean; s= standard deviation; SX =standard error of the mean.

46
Table 33. Triceps skinfold of youths 12-17 years of age weighing 85-89.9 kilograms,

by sex and age at last birthday:sample size, estimated population size, mean, standard deviation, standard error of the mean, and selected percentiles,

1966-70

United States,

Sex and age

Male

12 years ------

13 years ------

14 years ------

15 years ------

16 years ------

17 years ------

Female

12 years ------

13 years ------

14 years ------

15 years ------

16 years ------

17 years ------

n

5

5

13

10

15

2

2

7

7

5

N

13

13

35

32

47

8

5

32

22

17

I I I

Ill Percentile

x s s%

5th 10th 25th 50th 75th 90th

In millimeters

>’t

*

22.6

14.4

14.9

-k

*

30.9

25.4

30.7

*

>’?

5.61

4.96

5.74

*

*

4.68

10.55

2.49

+;

*

1.68

1.68

1.92

*

*

1.34

$.70

L.64

*

-k

9.5

9.8

7.8

*

*

22.4

9.7

28.3

+C

*

16.3

10.2

8.3

*

*

22.9

9.8

28.5

>’t

*

21.0

10.8

12.3

*

*

28.1

17.4

29.3

*

*

21.9

12.6

14.2

*

*

32.5

25.4

30.3

*

$<

29.0

19.1

21.1

*

*

33.7

35.4

30.9

*

*

29.8

20.7

25.6

*

*

34.9

40.0

35.0

95th

*

*

30.0

26.2

26.0

*

*

39.0

40.0

35.0

~ = sample size; N=estimated number of youths in population in thousands;

Z ~“~%m; S= standard deviation; S% = standard error of the mean.

47
Table 34. Triceps skinfold of youths 12-17 years of age weighing 90-99.9 kilograms,

by sex and age at last birthday:samplesize, estimated population size, mean, standard deviation, standard error of the mean

1966-70

, and selected percentiles, United States,

Sex and age

Male

12 years-------

13 years-------

3.4years-------

15 years-------

16 years-------

17 years-------

Female

12 years-------

13 years-------

14 years-------

15 years-------

16 years-------

17 years-------

n

1

2

7

8

11

19

4

3

2

9

6

N

2

7

26

26

37

78

10

10

6

29

20

I

*

*

27.4

16.7

17.7

20.7

*

*

*

31.8

32.9

*

*

7.25

4.05

4.08

6.93

*

*

*

4.60

7.56

Percentile

SE

5th 10th 25th 50th 75th 90th 95th

In millimeters

*

*

4.64

1.74

1.94

2.93

*

*

*

1.48

4.03

*

*

15.5

10.7

11.7

9.5

*

*

*

26.2

17.6

*

*

16.0

10.8

11.9

11.7

*

*

*

26.5

17.7

*

*

22.5

14.2

13.8

15.7

*

*

*

27.4

31.8

*

*

32.2

17.1

17.5

20.4

*

*

*

32.3

34.2

*

*

37.0

21.4

24.1

32.0

*

*

*

40.4

40.4

*

*

37.0

21.4

24.3

32.0

*

*

*

40.0

40.4

. = sample size; ~=estimated number of youths in population in thousands;

X ~“%m;

n

S= standard deviation; Sz = standard error of the mean.

48
Table 35. Triceps skinfoldofyouths 12-17 years of age weighing 100 kilograms or more,

by sex and age at last birthday sample size, estimated population size, mean, standard deviation, standard error of the mean, and selected percentiles, United States,

1966-70

Sex and age

Male

12 years-------

13 years-------

14 years-------

15 years-------

16 years-------

17 years-------

Female

12 years-------

13 years-------

14 years-------

15 years-------

16 years-------

17 years-------

n

Percentile

z s’ s%

5th 10th 25th 50th 75th 90th 95th

In millimeters

*

21.:

*

*

*

*

*

*

*

6.8;

*

*

*

*

*

*

*

2.6:

*

*

*

*

*

*

*

12.:

*

*

*

*

*

*

*

12.:

*

*

*

*

*

*

*

14.;

*

*

*

*

*

*

*

20.;

*

*

*

*

*

*

*

26.;

*

*

*

*

*

*

*

34.:

*

*

*

*

*

*

*

34.;

*

*

*

*

*

- NOTE: ‘??=sample size;lV=

X= mean; S=

estimated number of youths in population in thousands;

standard deviation; S: = standard error of the mean.

49
Table 36. Area of arm at triceps, estimated area of muscle and bone,,andestimated area

of fat for males and females 6-17 years of age: United States, 1963-70

I I

Sex and age

Male

6 years------------------------------------------

7 years------------------------------------------

8 years------------------------------------------

9 years------------------------------------------

10

11

12

13

14

15

16

17

years-----------------------------------------

years------------.----------------------------

years-----------------------------------------

years-----------------------------------------

years-----------------------------------------

years---------------.-------------------------

years-----------------------------------------

Female

6 years------------------------------------------

7 years------------------------------------------

8 years------------------------------------------

9 years------------------------------------------

10

11

12

13

14

15

16

17

years----------------------------------------

years-----------------------------------------

years-----------------------------------------

years-----------------------------------------

years----------------------------------------

years-----------------------------------------

years-----------------------------------------

years-----------------------------------------

Estimated

Ar~myf area of Estimated

muscle and area of

bonel fats

I I

In square millimeters

2,410

2,586

2,764

2,964

3,135

3,454

4,051

4,547

5,127

5>645

6,000

6,348

2,380

2,565

2,828

3,043

3,332

3,573

4,242

4,471

4,775

5,142

5,119

5,231

1,761

1,926

2,052

2,183

2,320

2,552

3,011

3,452

4,089

4,623

4,968

5,233

1,662

1,754

1,901

2,068

2,214

2,436

2,976

3,092

3,207

3,367

3,350

3,331

649

660

712

781

815

902

1,040

1,095

1,038

1,022

1,032

1,115

718

811

927

975

1,118

1,137

1,266

1,379

1,568

1,775

1,769

1,900

——

1.

2%%;&n;ed area of fat = area of arm - estimated area of muscle and bone.

50
Table 37. Comparison of skewness ratios between races and sexeslfor skinfolds of children and youths: United States, 1963-70

Comparative race or sex group

White ratio greater than Negro ratio ------

Negro ratio greater than white ratio ------

White ratio equal to Negro ratio ----------

Male ratio greater than female ratio------

Female ratio greater than male ratio ------

Male ratio equal to female ratio ----------

Triceps

7

16

1

18

6

0

Medial

calf

2

10

0

11

1

0

Skinfold

Sub -

scapular

15

8

1

13

11

0

Midaxillary

16

7

1

15

10

0

lWmber of times one ratio was greater than another, comparisons made by

either race or sex.

Suprailiac

4

8

0

11

1

0

age and

51
APPENDIX I

STATISTICAL NOTES

The Survey Design

The sampling plan of the third cycle of the Health

Examination Survey followed a multistage, stratified

probability sample of clusters of households in landbased segments in which a sample of the United States

population (including Alaska and Hawaii) aged 12

through 17 years was selected. Excluded were those

youths confined to institutions and those residing upon

any of the reservation lands set aside for use by American IncWms.

The sample design of Cycle III is similar to that

of Cycle H in that it utilizes the same 40 sample areas

and the same segments. The decision to incorporate

this feature into Cycle III was not made prior to the

selection of the second cycle sample although it is consistent with the early concept of a single program for

6-17 year olds. The final decision to utilize this identical sampling frame was made during the operation

of the second cycle program.

The successive elements for this sample design

are primary sampling uni~ census enumeration distric~ segment (a cluster of households); househol~

all eligible youths; and finally, sample youth. Every

eligible youth within the defined population has a known

and approximately equal chance for selection into the

sample.

The steps of drawing the sample were carried out

jointly with the Bureau of the Census; the starting

points were the 1960 decennial census lists of addresses

and the nearly 1,900 primary sampling ‘units (PSU’S)

into which the entire United States was divided. Each

PSU is a standard metropolitan statistical area (SMSA),

a county, or a group of two or three contiguous counties. These PSU’S were grouped into 40 strata so that

each stratum had an average size of about 4.5 million

persons. This grouping was done in a manner which

maximized the degree of homogeneity within strata

with regard to the population size of the PSU’S, degree

of urbsrdzation, geographic proximi~, and degree of

industrialization. The 40 strata were then classified

into four broad geographic regions of 10 s~ata each

and then within each region, cross-classified by four

population density classes and by tlie rates of population change from 1950 to 1960. Using a modified Good52

man-Kish controlled-selection technique, one PSU was

drawn from each of the 40 strata.

The sampling within PSU’S was carried out in several steps. The first was the selection of census enumeration districts (ED’s). These ED’s are small welldefined areas of about 250 housing units into which the

entire Nation was divided for the 1960 population census.

Each ED was assigned a “measure of size” equal to the

rounded whole number resulting from a “division by

nine” of the number of children aged 5-9 in the ED at

the time of the 1960 census. A sample of 20 ED’s in

the sample PSU was selected according to a systematic

sampling technique with each ED having a probability

of selection proportional to the population of children

5-9 years at the time of the 1960 census date. From each

ED a random selection of one measure of size (segment) was taken.

Minor changes required in the Cycle III design were

that it be supplemented for new construction to a greater

extent than had been necessary in Cycle II and that

reserve segments be added. Although it was the plan

for Cycle III to use the Cycle H segments, it was recognized that within several PSUfs, additional reserve

segments would be needed to avoid the risk of having

an insufficient number of examinees. This was prompted

by the fact that four of the PSU’S in Cycle II had yields

of less than 165 eligible children and several others

were marginal in their yield. In addition, there was a

3-year interval between Cycle II and Cycle III, so that

it was quite possible for some segments to have been

completely demolished to make room for highway construction or urban redevelopment.

The time available for examinations at a particular

location or stand, as they have been designated, is

necessarily set far in advance of any preliminary field

work at the stand. Therefore, the number of examinations that can be performed at a particular location is

dependent upon the number of examining days available.

At the majority of locations the number of days available, excluding Saturdays, is 17. At the rate of 12 examinations each day, this provides for 204 examination

slots. Examinations are conducted on Saturdays if for

some reason it is necessary. Because of rescheduling

for cancellations or no-shows, the maximum number

of youths that is considered for inclusion in the sample
is 200. When the number of eligible youths exceeds

this number, subsampling is performed to reduce the

number to manageable limits. This is accomplished

through the use of a master list which is a listing of

all eligible youths in order by segment, serial number

(household order within segment), and column number

(order in the household by age). After the subsampling

rate has been determined, every rsth name on the list

is deleted, starting with the yth name, y being a rsndomly selected number between 1 and n. Youths who

are deleted from the Cycle III sample but who were

examined in Cycle 11as well as any twin who may have

been deleted are, if time permits, scheduled for an

examination for inclusion only in the longitudinal study

portion or twin study portion of the survey. Their data

are not included in the report aa part of the regular

sample.

Since the strata are roughly equal in population

size and a nearly equal number of sample youtha were

examined in each of the sample PSU’s, the sample design is essentially self-weighting with respect to the

target population; that is, each child 12 through 17 years

old had about the same probability of being drawn into

the sample.

The adjustment upward for nonresponse is intended

to minimize the impact of nonresponse on final estimates by imputing to nonrespondents the characteristics of “similar” respondents. Here “similar” respondents were judged to be examined youths in a

sample PSU having the same age (in years) and sex

as those not examined in that sample PSU.

The poststratitied ratio adjustment used in the

third cycle achieved most of the gains in precision

which would have been attained if the sample had been

dr~wn from a population stratified by age, color, and

sex and made the final sample estimates of population

agree exactly with independent controls prepared by

the U.S. Bureau of the Census for the noninstitutional

population of the United States aa of March 9, 1968

(approximate midsurvey point) by color and sex for

each single year of age 12 through 17. The weight of

every responding sample child in each of the 24 age,

race, and sex classes is adjusted upward or downward ao that the weighted total within the class equals

the independent population control.

A more detailed description of the sampling plan

and estimation procedures is included in Vitul and

Health Statistics, Series 2, Number 43,19 “Sample Design and Estimation Procedures for a National Health

Examination Survey of Children,” and in Series 1,

Numbers 1,20 5,3 and 8,4 which describe the plan

and operation of the first three cycles of the Health

Examination Survey (HES).

Some Notes on Response Rates

As mentioned previously, the sample designs of

the second and third cycles of the HES were similar.

NOTE The list of references follows the text.

Differences did occur, however, in response rates of

various subgroups of these samples and these differences deserve some consideration here.

Most importantly, the number of youths selected

for examination increased from 7,417 in Cycle II to

7,514 in Cycle III. The response rate, that is, the number of youths selected who were actually examined,

decreased from 96 percent in Cycle H to 90 percent in

Cycle III. Of the examined youths of Cycle II, 13.86

percent were Negro compared with 14.76 percent of

those examined in Cycle 111. This difference does not

reflect a difference in the percentage of Negro youths

selected for examination, but instead, a smaller decrease in response rate for Negro youths between the

two cycles than waa the case for the white youths. In

actuality, 13.8 percent of the sample selected for examination was Negro in Cycle III corresponding to 13.5

percent for Cycle II. However, whereas the response

rate for white youths dropped from 95.6 percent in

Cycle H to 89.1 percent in Cycle III, the response

rate for Negro youths dropped a far lesser degree

from 98.4 percent to 96.6 percent. Thus, better relative

response from the Negro portion of the sample yielded

a greater percentage of these youths actually examined

during Cycle 111 than was the case during the previous

sample.

Examination of sample sizes in this report clearly

shows that at every age group there were fewer girls

actually examined than there were boys of the same

age. This again is not attributed to differences in numbers of youths selected in the sampling design, but

rather to the following differential response rates between maies and females:

Age Male Fatrde

12 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93.5 91.3

13 . . . . . . . . . . . . . . . . . . ... . . . . . . . . . . . . . . . . . 93.2 91.9

14 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91.7 90.7

15 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91.6 87.9

16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89.8 87.7

17 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87.6 81.8

Total . . . . . . . . . . . . . . . . . ... . . . . . . . . . . . . . 91.4 88.7

Note that at each age group the response rate for Imys

exceeded that of girls.

A similar analysis of response rates can be done

by age, race, and sex as follows:

White

Age

Negro White

male male female f252

12 . . . . . . . . . . . . . . . . . . . . . . 92.6 99.0 90.1 98.9

13 . . . . . . . . . . . . . . . . . . . . . . 92.5 98.8 91.1 96.8

14 . . . . . . . . . . . . . . . . . . . . . . 91.0 97.8 89.6 98.2

15 . . . . . . . . . . . . . . . . . . . . . . 90.7 97.7 86.4 98.6

16 . . . . . . . . . . . . . . . . . . . . . . 89.2 95.0 66.6 93.0

17 . . . . . . . . . . . . . . . . . . . . . . 86.5 95.8 80.2 91.4

Total . . . . . . . . . . . . . . . . 90.5 97.6 87.4 95.8

The above clearly indicates that for all ages under

consideration in Cycle 111of the HES, the response rate

53
for Negro youths exceeded that of white youths of the

same sex and age.

Reasons for differences in response rates are

many but may range from the incentive to get examined

in order to miss a day of school, to fear of the examination itself, to inhibitions with respect to being

examined. The worst response rate was recorded for

the oldest girls. i.e.. 17-year-old females.

Parameter and Variance Estimation

As each of the 6,768 sample children has an

assigned statistical weight, all estimates of population

parameters presented in HES publications are computed

taking this weight into consideration. Thus ,x, the estimate of a population mean,” p,” is computed as follows:

Z=~~Wi Xi/ZWi, where Xl is the observation or

measurement taken on the i th person and Wi is

the statistical weight assigned to that person.

The HES has an extremely complex sampling plan,

and obviously the estimation procedure is, by the very

nature of the sample, complex as well. A method is required for estimating the reliability of findings which

“reflects both the losses from clustering sample cases

at two stages and the gains from stratification, ratio

estimation, and poststratification.” 2

The method for estimating variances in the HES

is the half-sample replication technique. The method

was developed at the U.S. Bureau of the Census prior

to 1957 and has at times been given limited use in the

estimation of the reliability of results from the Current

Population Survey. This half-sample replication technique is particularly well suited to the HES because

the sample, although complex in design, is relatively

small (6,768 cases) and is based on but 40 strata. This

feature permitted the development of a variance estimation computer program which produces tables containing desired estimates of aggregates, means, or

distributions, together with a table identical in format

but which contains the estimated variance of the estimated statistics. The computations required by the

method are simple, and the internal storage requirements are well within the limitation of the IBM 360-50

computer system utilized at the National Center for

Health Statistics.

Variance estimates computed for this report were

based on 20 balanced half-sample replications. A half

sample was formed by choosing one sample PSU from

each of 20 pairs of sample PSU’S. The composition of

the 20 half samples was determined by an orthogonal

plan. To compute the variance of any statistic, this

statistic is computed for each of the 20 half samples.

Using the mean as an example, this is denoted ~.

Then, the weighted mean of the entire, undivided sample

NOTE: The list of references follows the text.

{~) is computed. The variance of the mean is the mean

square deviation of each of the 20 half-sample means

about the overall mean. Symbolically,

and the standard error of the mean is the square root

of this. In a similar reamer, the standard error of

any statistic may be computed.

A detailed description of this replication process

by Philip J. McCarthy, Ph. D., has been published.21

Standards af Reliability and Precision

All means, variances, and percentages appearing

in this report met defined standards before they were

considered acceptably precise and reliable.

The rule for reporting means and percentiles consisted of two basic criteria. The first criterion was

that a sample size of at least five was required. If this

first criterion was met, then the second criterion,

that the coefficient of variation [i.e., the standard

error of the mean divided by the mean (sX@)] was to

be less than 25 percent, must have been demonstrated.

Thus, if either the sample size was too smalI, or the

variation with respect to the mean was too large, the

estimate was considered neither precise nor reliable

enough to meet the standards established for publication.

To illustrate these criteria, in table 21 all values

of the distribution of skinfolds for 14-year-old males

weighing less than 30 kilograms were replaced by asterisks (*) since there were less than five people of

that age, sex, and weight. Furthermore, in that same

table, although there were five 13-year-old boys, the

distributions of skinfold values are also replaced by

asterisks because the standard error with respect to

the mean exceeded the criteria previously stated.

Hypothesis Testing

Although this report is primarily descriptive, it

is often desirable to make statistical comparisons

between two groups such as males and females or

1Z-year-olds and 13-year-olds. Classically, if a statistician wishes to test the difference between two m&ms

(or, put differently, to test whether two samples could

have been drawn from the same population), he could

do so by setting up a normal deviate in which he would

utilize the means and standard errors of the means as

computed from the samples. The statistic

is then compared to a table of normal deviates to determine whether or not there is, in fact, a difference

54
between the two groups. (Note that the above makes the

assumption that the two groups are independent and

that S # + S 3.)

While the technique may appeal to many, in the

analyses of this report this technique is not used for

two basic reasons:

(1)

(2)

Use of the z statistic makes necessary the

assumption of normality. As is clearly shown

by the percentile distributions of the variables

considered in this repo~ t, this assumption is

badly violated.

Because of the many breakdowns of the HES

sample, innumerable tests of this nature could

be performed and, with each new test, the

probability of rejecting a hypothesis incorrectly

may be .05, but if 10 such tests are performed,

the probability of making at least one mistake

somewhere in those 10 tests is something

closer to .50.

It was therefore decided to place the greatest emphasis on a relationship remaining consistent over both

sexes (or races) and all ages under consideration. In

other words, to say that “girls have median triceps

skinfolds greater than boys for all ages between 12 and

17 years” has far more meaning and interpretability

than to say “the mean triceps skinfold for 12-year-old

girls is significantly greater than the corresponding

mean for 12-year-old boys, and the mean . . . . for 13-

year-old girls is significantly greater than tbe mean

for 13-year-old boys, 14-year-old girls, etc.,” as determined by a normal deviate. In these analyses, consistency rather than a statement about a succession of

individual probability levels is the factor considered

most important in demonstrating a relationship.

Analysis of Correlations Among Skinfolds

For each of the 6,768 children in the sample five

skinfolds were recorded. The correlation coefficients

were computed for each of the 10 possible pairs of

these five skinfold measurements in the following manner:

r= I

2 w, Zw, X,Y, - Zw, X,(zw,y)

d[zw, Zw, Xf-(zw, X,) ’lrxviMi%+’i)’l

where WI is the weight assigned to the i ‘h individual

and X and Y are the two skinfold measurements being

correlated.

Three correlation coefficients were computed for

each of the 24 age-sex-race categories. The results

are presented in table 14. As described in the text, it

was decided to rank, witbin each age-sex-race group,

the five correlation coefficients under consideration.

The distribution of these ranks is shown in table 15.

Imputation

The necessity of arriving at a workable imputation

scheme for Cycle 111of the HES was dictated by the

fact that each individual carries a separate and unique

statistical weight, i.e., the number of individuals in the

United States population he is said to represent. The

decision to drop from the sample such an individual

due to missing or erroneous values on some number

of variables would not be satisfactory unless the statistical weight was somehow redistributed. The extent

of bias introduced in this manner would depend upon

the scheme chosen for the redistribution of the individual’s statistical weight and would carry along with

it the major disadvantage of having unweighed sample

sizes differ from variable to variable (thus making correlation procedures more complicated), while, of

course, the weighted sample sizes would remain constant.

A regression method of imputation which was selected for the analysis of HES body measurements was

desirable and possible for several reasons. First, the

number of problem cases was small enough so as not

to be unwieldy. Second, the various body measurements

collected on an individual are highly correlated and,

as such, one would like the imputed value to be harmonious with the other valid measures for that individual.

To simply impute a group mean or a randomly selected

value to an atypical individual in place of either a nonexistent or an existing but obviously incorrect measurement while ignoring the other valid information on

that same individual would be undesirable.

Third, the bias introduced by a regression scheme

would clearly be less than would arise if individuals

with missing or questionable bits of information were

excluded from the sample and their statistical weights

redistributed. Fourth, this system has the advantage

of holding both the weighted and unweighed sample

sizes constant from variable to variable thus facilitating any correlations or cross-tabulations desired.

Thus, an elaborate regression scheme was utilized

to impute body measurements of the third cycle of the

HES.

The procedure was as follows: From the total

6,768 subjects on whom some body measurements were

performed, 26 subjects for whom there was one or

more missing value were temporarily dropped and

four files were created from the remaining 6,742 subjects. The files were white males, Negro males, white

females, and Negro females. It was from these subjects that the prediction equations were finally developed.

In a typical case, a subject (for example, a 12-yearold Negro male) might have a body weight recorded

which is so low as to raise the question of whether there

was an error somewhere in the data preparation process. However, despite this extremely low value, his

record would be otherwise complete. Since all the other

55
variables are recorded for this individual, an estimate

for body weight is derived based on all the other information available and it is possible to conclude that

the recorded measurement is possible considering the

youth’s other dimensions or that the recorded value

is an obvious clerical error and should be changed.

Thus, the file with the Negro males who all have complete records is tapped and a stepwise regression is

calculated, with body weight the dependent variable.

All the remaining variables are eligible for inclusion

into the equation with the following restrictions:

(1)

(2)

Age must be the first variable added into the equation, irrespective of the correlation between age

and the dependent variable.

So long as adding a new variable contributed at

least .005 (%percent) to the coefficient of multiple

determination (R2), it was included. If the contribution was less than that, the equation was frozen with all the variables which did add at least

that much to R2. (No equation included more than

eight independent variables.)

The resulting equation may be of the form

Y= a+~lX~+~zXz+f13Xa+...6k xk

where Y is the predicted sitting height, a, @l,132,B3,etc.

are the coefficients generated by the regression, and

Xl, X2, X3, etc. are the independent variables. By inserting the recorded values for this subject of X1,X2,X3

up to xk ( k being the number of variables contributing

significantly to R 2, kS8) into the equation, a prediction

is arrived at for body weight. A value imputed in this

manner is superior to other possible methods since

all the relevant information is utilized and allows an

extremely large or small person to be assigned a similarly large or small imputed value.

In actusli~ there were only 19 youths in Cycle 111

of the HES whose values for any of the five akinfolds

were either missing or highly questionable on the original data tape.

NOTE: The list of references follows the text.

To determine whether a skinfold measurement was

“questionable,” extremes of the distributions of each

variable were examined case by case. (Although useful,

this procedure allows some highly deviant values to go

undetected. For example, hidden in the distribution of

triceps skinfolds maybe an extremely thin individual who

had a mispunched skinfoldfsr too large for his thin build

and MS other four skinfold measurements but nevertheless within normal bounds for the entire distribution

of all triceps skinfolds from the entire HES sample.)

But the magnitude of the problem of bad or missing

skinfold data in the HES is very small and oversights

such as this will not have an appreciable collective

effect.

A problem much more prevalent in these skinfold data than those described above is that of “tight

skin.” In some circumstances, the skin is so tightly

bound to the underlying tissue that it cannot be picked

up into a double fold by the technician. Code 00.0 was

used by the technician to indicate that he was unable

to read the skinfold measurement rather than implying that the skinfold existed but was so small that it

measured zero.

There were a total of 83 subjects on whom tight

skin was recorded for at least one of the skinfolds;

and, as can be seen, this most often occurred in the

medial calf fold. The frequencies of occurrence of

tight skin were as follows:

Of course.

Triceps: 5

Subscapular: 6

Midsxillary: 4

Suprailiac: 10

Medial calf: 67

several vouths had “tight skin” recorded on more than one of the skinfolds.

A complete description of the problems, the alternatives, and the selected procedure for use in imputation of all the other HES body measurements can

be found in a separate document.22 In addition, a com -

plete log was

Cycle III data

request.

kept of all changes made on the original

and these may be made available upon

ooo —

56
APPENDIX II

DEMOGRAPHIC VARIABLES

Regional and demographic characteristics by which

the population has been classified for this report are

defined as follows.

Age and Sex

Population was classified into 12 age-sex groups—

the six ages 12-17 years by sex. Birth certificates

were obtainable for verification of age for 92 percent

of the youths. Age stated by the parents was accepted

as the true age for the other 8 percent. Age is expressed as years attained at last birthday.

Race

Skinfolcls were reported by race for white and

Negro youths. Youths of other races were not sampled

sufficiently for comparison purposes; these youths

represented only 0.32 percent of the sample.

Region

Regional data are presented for four regions of

the continental United States.

Re@”on States Included

Northeast ------- Maine, Vermont, New Hampshire,

Massachusetts, Rhode Island,

Connecticut, New York,

Pennsylvania, New Jersey

Midwest -------- Minnesota, Wisconsin, Michigan,

Iowa, Missouri, Illinois, Indiana,

Ohio

South ----------- Delaware, Maryland, Virginia,

District of Columbia, West Virginia,

Kentucky, Temessee,

North Carolina, South Carolina,

Georgia, Florida, Alabama,

Mississippi, Arkansas, Louisiana

West ----------- Washington, Oregon, Idaho, Montana,

North Dakota, South Dakota,

Wyoming, Nebraska, Kansas,

Colorado, Utah, Nevada, California,

Arizona, New Mexico, Texas,

Oklahoma

57
TECHNIQUES

Introduction

APPENDIX

OF MEASUREMENT

Ill

AND QUALITY CONTROL

The major methodological concerns involved in the

measurement of skinfold thickness are:

In normal, healthy, and well-nourished individuals, ● The calipws utilized. There are a number of calias much as 25 percent of the total mass of the body

can consist of fat cells in quantities large enough to

form a definite adipoae tissue. Although a significant

proportion of this fat is located internally, often

surrounding organs such as the kidney, more than

half of it is found subcutaneously where it “blankets”

the individual. In a number of regions of the tidy the

adipose layer may be ,! liftedll with the fingCXS, i.e.,

pulled away from underlying tissues, to form a skinfold. The skinfold therefore consists of a double layer

of subcutaneous &t and $kin whose thickness may be

measured with appropriate equipment and by exercising

reasonable care (figure I).

pers now available which give comparable results.

Figure II illustrates the Lange caliper, now mamtfactured by Cambridge (Maryland) Scientific Industries,

Inc., and used in the Health Examination Survey. As

with all acceptable calipers, it is spring-loaded to the

closed position and compresses the fold with a constant

pressure of 10 grams/mm.2 throughout its range of

openings. The calipers are readily calibrated using a

standard aluminum step wedge with widths in increments of 10 mm. If the needle indicator strays even

slightly from the exact mark, it can be realigned very

easily. Extensive data available at Cambridge Scientific

Industries demonstrate that the spring loading is virBone

Figure 1. Diagram of the technique for measuring a skinfold, a double layer of

subcutaneous fat and skin. In this case, the triceps skinfold is being measured

with the Lange caliper. (Drawing courtesy of Muriel Kirkpatrick,Dept. of Anthropology, Temple University)

58
Figure I 1. Lange cal i per .

tually constant and that occasional slight indicator segment of the skin must be “pinched” in order to

fluctuation is the only drift in the instrument; when the form a fold than when the adipose tissue is poorly

needle is realigned, the measurement becomes precise developed, aa it is on the dorsum of the hand. For

again. a given site the width of the skin should be mini.

● The technique utilized. The most comprehensive real, still yielding a well defined fold.

description of the actual technique is given by Bro~ek c

as follows (see figure I):

The “skin” ahouldbe lifted bygrasping firmly the

fold between the thumb and the forefinger. A firm

grip, not exceeding the pain threshold, eliminates

or at least substantially reduces the variations

in the apparent thickness of skinfold that would

result from wide differences in the pulling force

of the fingers.

The width of the skin that is enclosed between the

fingers is an important factor. It cannot be standardized, in its absolute size, for all the sites of

the body. With a thick subcutaneous layer a wider

c From BroZek, J., The measurement of body composition, in M. F. A.

Mont agu, e d., .4 n Introduction to Physical Anthropology, ed. 3,

1960, pp. 637-686. Courtesy of Charles C. Thomas, Publisher,

Springfield, Illinois.

The depth of the skinfold at which the calipers are

placed on the fold also requires comment. The two

sides of the fold are not likely to be parallel, when

the skin is lifted by one hand, being narrower

near the crest and larger toward the base. When

the calipers are placed at the base, the resulting

measurement is too large. Here, again, the correct

distance J70m the crest is defined as the minimal

distance from the cvest at which a true fold, with

surfaces approximately pwallel to each other and

to the contact surfacesof the calipevs, is obtained

upon the application of the calipers to the skin.

Some caliper models only approximate but do not

actually achieve the parallelism of the contact

surfaces. However, such parallelism is a desirable

feature of the calipers. In very obese individuals at

some sites no true skinfolds, as defined above,

59
can be obtained. The measurements are still useful as indicators of fatness but the “skinfold”

measurements are then larger than a double value

of skin plus the subcutaneous layer, taking into

account the compression of the tissues by the

calipers. It is recommended to lift the skinfold at

a distance of about 1 cm. from the site at which the

calipers are to be placed and the skinfold measured.

● The sites selected for measurement. The thickness

of the subcutaneous tissue may be measured at any

number of sites, and the choice of a site is dictated

largely by the problem under investigation. At the same

time, certain sites have become more or less standardized as locations which are readily accessible,

which may be more accurately measured, which have a

layer of fat of relatively uniform thickness, and which

serve aa a reasonable sample of all the subcutaneous

fat of the body. For Cycle 111five sites were selected

(1) ts+ce@, over the triceps muscle halfway between

the elbow and the acromiaI process of the scapula, with

the skinfold parallel to the longitudinal axis of the

upper arm; (2) subscapukw, i cm. below the inferior

angle of the scapula in line with the natural cleavage

lines of the skin; (3) mkiiwilkvy, in the midaxillary

line, but with the fold perpendicular to it, midway

between the nipple and the umbilicus; (4) sups’ailiac,

just above the iliac crest in the midaxillary line, with

the fold perpendicular to i~ and (5) medtizl calf, on the

medial aspect of the Iegnear its greatest circumference,

the fold running parallel to the long axis of the leg.

Diagrams of the five sites are shown in figure III.

Figure Ill. The five skinfold sites: (I) subscapular, (2)

triceps, (3) midaxiilary, (+) suprailiac, (5) medial calf

(leftcalf skinfoldshownfor convenience).

HES Measuring Technique

Trained observers measured all skinfolds to the

nearest 0.5 mm. The values were read aloud to a recorder, also a trained measurer, who repeated aloud

each number back to the observer as it was recorded

in the proper space on the record form. This repetition

served both as a doublecheck to the measuring technician and to reduce the recorder’s errors. The measurement was repeated, and if it did not coincide with

the first one, a third one was taken.

All skinfolds and body measurements were performed in a regular sequence to minimize the number

of position changes the child was required to make.

The sequence is illustrated on the measurement recording form (figure IV).

All of the individuals performing body measurements in the HES were experienced X-ray technicians

who had been trained in anatomy and the identification

of specific body landmarks. In addition, X-ray technicians tend to work well with people and are skilled

in giving the examinee verbal orders along with the

necessary handling to achieve proper positioning.

Each technician received more than a month of

fntensive training before being considered profici ent in

making body measurements. In this training, he became skilled with the equipment, the precise locations

of the body at which the measurements were to be taken.

and the technique of measurement itself. The major

sources of measurement error by the trainee were

improper positioning of subject’s body, improper selection of specific body landmarks, and improper technique in applying the calipers. Incorrect reading from

the instrument (usually transposition of numbers) also

occurred. The measurements of each technician were

carefully compared with those of the other three and

with the measurements of the two supervisors (Dr.

Peter V. V. Hamill, the medical advisor, and Dr.

Francis E. Johnston, the anthropologic consultant) before they were officially accepted as recordable data.

Broadly conceived, training and quality control

have two major goals-(1) to substantially reduce the

variability introduced by errors of measurement and

(2) to assess the magnitude of the remaining residual

error. The achievement of the first goal requires not

only suitable initial training but also a persistent ongoing system of quality control. Achieving the second

requires the construction of experiments designed to

quantify specific components of the error of measurement.

Training and quality control for taking body measurements consisted of six identifiable procedures, some

emphasizing the training component and some the

assessment of quality.

(1) Careful training of the examiners.

(2) Periodic direct observation by the medical advisor

and the anthropologic consultant as measurements

60
(3)

HEUTH SumAuon SIWEV-111

BODY MEASUREMENTS

Mttmmensmts is cm. wdsss otherwisespecz~ed.

—

l—

z

— w,

8-1

12-1

16-1

20-2

n-a

m-c

324!

WOY

CUD

SEATED

MEA2.

W.

CERVICAU HEIGtil ———@—

A— HEIGHI ———*—

SADIAL HEIGHT —*—

S7WON HEIGHl ———0—

IUAC CSEST HEIGHT ——e—

1~ HEIGW ———*—

ITBIAL HEIGHT —— — ● —

sum

●—

SITTING HEIGHT (Em+) —— —*—

THIGH CLEMAKE ——*—

S?HYRDN HEIGHT — — ● —

roar SRsADm ——o—

I

❑ Lmwr

1d TOE REunvE

m ad TOS ❑ Shorlw

❑ S’arrw

ANKLE 5SEADTH ——*—

KNEE 5READTH — —*—

ELBOW MEADTH — —*—

WRIST BREAOTH ——*—

2rd (I*) FINGER

I

•l kr

RELATIVE TO ❑ Sk.li.r

4* (Nw) FINGER

❑ s...

MEDIAL W

SKINFOLO (mm.) ——*—

5TANDINGHEIGHT —— —0—

EMENTS NOT DONE OR SIDE VARIED->

8-10 SIZYGOAWTC MEADTH — —*—

11-13 BIGONIAL 5READTH —0—

14-16 nmw.usow mEArmH —*—

17-19 SEAT 5READTH ——e—

~20-2s FOOT LENGTH —m————

I 5TAS4DING

m-as slAcRoMIAl SREAOTH —*—

26-21 SJCRISTALmEAoTH — —*—

!29-31 BITROG+ANTERK 5SEADTH ——0—

I

32-34 UWER ABM GIRTH ——*—

3547 FO- GIRTH ——*—

SS-61 CHEST GIFTH —— —*—

42-65 WAIST GIRTH

——*—

46A9 HIP Glm —0—

50-52 CALF GIKIH

——*—

5G-55 TRICEPS SKINFOLD (mm.)

—*—

56-58 SUSSCAFWAR SKINFOID (...) — —0—

59-61 LATERAL

CHEST SKINFOI.D (mm.)

——*—

62-64 SUPDA-IUAC SKINFOLD (mm.)

—*—

65-6S WEIGHT (lb.)

—0—

I

ijj wbicb and give reason:

~!:a SAJAME NO. ,,.5,

Figure IV. Bodymeasurementrecord ing form.

were being taken with correction of errors when

necessary.

Practice and retraining during dry runs. The first

day at each location (that is, approximately one day

a month) was devoted to dry runs, during which all

equipment was retested and recalibrated and regular practice procedures were carried out. Each (4)

technician and either a supervising technician or

the supervisors measured one or more people

several times. Discrepancies in measurements

were discussed and any steps necessary to improve the techniques were taken. Although these

were primarily trsining sessions, they afforded an

ongoing informal assessment as to the quality of

the data.

Approximately every 6 to 9 months an intensive

evaluation of measurement technique was conducted by the supervisors. These sessions lasted

61
(5)

(6)

2 days and involved the measurement, each time,

of two boys. One boy was quite fat and the other

was linear in physique. On the first day both boys

were measured by each of the four technicians

with the supervisors acting as recorders. The

following day the procedure was repeated, thus

giving both inter-observer and intra-observer comparison of sets of measurements. It was only at

this time that the technicians were allowed to see

the previous measurements andto compare theirs

with their ownandwith the other three sets. Major

discrepancies were noted andattempts were made

to establish the sources of differences and to

eliminate them. In addition, such matters as underlying principles of growth and development and the

significance of the survey were discussed.

These sessions were intended to include assessment of errors due to technician differences,

to differences in physiques of subjects, to the site

of the skinfold, as well as to interactions among

these sources of error. For a variety of reasons,

e.g., number of subjects and a greater number of

technicians in Cycle 111than originally specified in

the model for the analysis of variance, the assessment was ultimately abandoned.

A daily instrument chkck was performed on the

calipers using the step wedge as described in the

section “Calipers Utilized,” earlier in this appendix.

Several additional calipers were on hand both

to enable the staff to periodically return the instruments to the factory for cleaning and for doublechecking their precision and to insure against the

loss of data in the event of instrument loss or

damage.

The analysis of a set of 301 replicate examinations,

taken during 30 stands over the 4 years of Cycle

III, provided an estimate of tbe magnitude of

measuring error. These data are the subject of the

detailed analysis in the following pages and are

judged to provide a fair estimate of the actual

residual variable measurement error as it occurred during Cycle HI measurements of skinfolds.

Surveillance and Evaluation of Residual

Measurement Process Error

The three following sections are extracted from a

recent publication, Quality Control in a National Health

.&umination Survey. 22This unusually lucid and wellorganized report on quality control was written by

Wesley Schaible, the quality control officer of tbe HES.

Material within brackets has been added to focus the

discussion on skinfold measurements.

NOTE: The list of references follows the (ext.

Monitoring Sysfems

Despite effo~ ts to reduce measurement errors,

residual errors of a magnitude large enough to warrant concern occur with some regularity [in any anthropometric survey]. There is, therefore, a real and

urgent need to have a system whereby these residual

errors can be monitored. The concept of quality control is based on the desire to obtain end products of a

certain quality. Thus, one of the main purposes of a

monitoring system is to indicate whether the measurements produced by a certain measurement process

attain the desired quality. A second purpose is to make

possible quantitative summary descriptions of residual

measurement errors to aid in the interpretation of

survey data.

The most extensive system of monitoring used in

the HES in Cycle 111was the collection and evaluation

of replicate data. Replicate measurements are useful

for a variety of purposes—for example, as a means of

increasing precision of estimates of individual measurements, as a training technique, and as a monitoring

system which includes the objective of final evaluation

of measurement errors. These objectives are not incompatible, and replicate data collected primarily for

one of these objectives often indirectly, if not directly,

accomplish one or both of the remaining two. For this

reason replicate data are most often collected with a

combination of these objectives in mind. The single

most important source of replicate data in Cycle 111was

the replicate examinations, in which approximately 5

percent of the regular examinees were returned to the

examination center for a second complete examination

except for drawing blood and taking X-rays.

Biases ond Controls in Replicate Measurements

A major source of uncertainty in estimates derived

from replicate measurements is in the inability to make

the replicate measurement under precisely the same

conditions and in the same manner as for the original

measurement. This uncertainty is difficult to evaluate

and most attempts to do so are restricted to subjective

statements concerning the direction and/or size of the

bias and the need for concern in the analysis of data.

Several policies regarding Cvcle HI replicate

examinations were specific in tile attempt to obtain

measurements taken under the same conditions and in

the same manner. Replicate examinations were not

conducted during a specific time, but whenever possible were interspersed among the regular examinations. An original examination was given priority over

a replicate examination in that none was scheduled if

it occupied time needed for a regular examination. In

practice there was often space to interject replicate

examinations il the schedule without interfering with

regular examinations. However, this priority plus the

fact that replicates were drawn from those examined

62
increased the likelihood that a replicate examination

would be scheduled toward the end of the examination

period. Nevertheless, the attempt to space the replicate

examinations in the schedule was a valuable policy

in that the interspacing of replicate and original examinations created an atmosphere more conducive to the

replicate examination’s being conducted in essentially

the same manner aa the original.

The examiners had been informed of the purpose

and importance of the reexaminations. It was emphasized

that they should not vary their procedures on a replicate examination or in any way try to collect “better”

data than they normally would. Thereafter, the conduct

of a replicate examination was not given any greater

emphasis than any other instruction since overemphasizing “sameness” might have created more bias

than it should have eliminated.

At the time of the ori~”nal examination neithev the

obscwvey nov tile examinee hnew whether or not the

e%minee would be retuvnedfora replicate examination.

During the replicate examination, observers were not

specifically informed that an examinee was a replicate

although no attempt was made to conceal this fact since

in an examination as lengthy as that given in HES the

examinee would undoubtedly be remembered by several,

if not all, examiners. Even though an examinee might

be remembered, it was extremely unlikely that an

examiner would remember a specific measurement

after a time lapse of 2 or 3 weeks. Some bias might be

introduced by the examiner’s knowledge of the replicate

status of an examinee, but generally this bias would

seem quite small when compared to the measurement

error and in some cases to the biases associated with

the knowledge and familiarity gained by the examinee

during the original examination. Examinee bias can be

important, especially in measurements for which a

response is elicited or when the true value of the

measurement has changed because of a time lapse.

Since the time lapse was usually 2 or 3 weeks, some

appreciable changes might occur in certain measurements such as weight. However, for most of the data

collected the actual change [over time] can only be very

small, so this effect may usually be neglected. [For

example, the examinee’s previous experience is much

more likely to affect, to some extent, the true repli -

cability of the psychological tests and those physiologic

tests requiring high levels of subject participation such

as the treadmill and spirometry; but on those procedures

in which the subject is passive, such as EKG and skinfold measurements, with very little learning involved,

the effect of the previous experience is almost zero in

Cycle III.]

Replicate data were obtained on approximately 70

percent of those selected for such examinations. One

explanation for this low rate is that the persuasion and

followup efforts were not as intensive as for regular

examinees. This is a partial result of giving priority

to regular examinees if interviewer or examination

time was limited. There also seems to be an increased

objection to returning for a second examination, as

demonstrated in the most frequent reasons for refusal:

“One time is enough” and “I can’t miss school again.”

Selection of Replicbte Examinees

The selection of Cycle 111examinees for replicate

examinations was random witbin certain restrictions

imposed by practical considerations. One of the restrictions was that replicate were selected only from

those examined during the first week and a half of the

approximately 3?4 weeks of examinations at any one

location. This time period was chosen to faciiitaie the

interspersing of replicate examinations with originals

in the examining schedule without interfering with the

time allotted for original examinations and without

scheduling additional time to accommodate replicates.

In a voluntary survey it is obviously impossible to

follow a statistically random process in scheduling

subjects, so those scheduled during the first week and

a half are not, in the strict sense, a random sample of

all those scheduled, though they may be randomly

distributed for those features which are significant.

Evidence that replicates might be considered “representative” is found in the fact that youths of certain

ages, locations, incomes, etc., are not routinely more

likely to be scheduled during any particular segment

of the examination schedule. However, the availability

and desires of the subjects do influence the composition of the replicate sample. For instance, an examinee whose participation in an original examination

was achieved only after repeated contacts by survey

personnel is more likely to have been excluded from

a replicate examination since it is unlikely that he

would have received an original examination during the

first week and a half. The schedule of locations considering time of year, sequencing of examinations,

relation to other events which might make subjects

more or less available, and other related aspects give

no obvious discriminatory factor. After examining these

and other relatively minor considerations there appears

to be no reason to believe that the subjects scheduled

and examined during the first part of a stand differ

from those scheduled and examined during the latter

portion of a stand with respect to the data gathered.

Another restriction on complete randomness in the

selection of examinees for replicate examinations was

the exclusion of those examinees who were “geographically inconvenient” to the examination center. “Geographically inconvenient” was arbitrarily defined as a

distance of 30 miles or greater; although if conditions

dictated, exceptions were sometimes allowed. A primary consideration in choosing a site for the examination center was the centrality of the location in

relation to the sample segments (a segment is a

cluster of households). Since segments were drawn

with probability proportional to population, most seg63
ments were in relatively populated areas; and so the

examination center was also in or adjacent to a

relatively populated area. Therefore, the subjects deleted by this 30-mile restriction usually resided in

relatively less populated areas; so this reS&iCtiOn may

create a bias in the replicate data if, in fact, characteristics and errors of concern differed by population

density. Even if differences did exist, the total effect

of this restraint was not great since it excluded only

approximately 10 percent of the eligible examinees.

There were other minor restrictions of medical and

operational nature imposed on the complete randomness of the replicate sample, but they were not readily

associated with large differences. Also they deleted at

most only 1-2 percent of the eligible examinees and

for these reasons are of small consequence.

Since the purpose of replicate examinations is to

giveinformation about errors, the matter of concern

between those excluded and those eligible for selection

is not the possible differences in the values of messurements but the possible differences in the errors

associated with the measurements as shown by the

discrepancy between two measurements on the same

subject. It should also. be noted that although subjects

did influence measurement errors [for some types of

examinations], the environment, procedures, and examiners were also highly influential. The consideration

of these additional influences causes a completely

random selection of subjects to be of somewhat less

concern.

(Note: This concludes the material extracted from

Schaible’s paper.)

Evaluation of Residual Measurement

Error in Skinfold Measurements

The residual error of measurement was estimated

from a set of 301 replicate examinations conducted, as

outlined below, during Cycle III of the HES.

Body measurements were taken on 6,768 youths

and these children comprised the HES Cycle 111sample.

At 30 of the 40 locations (or stands) visited throughout

the United States, replicate body measurements were

obtained on 301 children. That is, an average of 10

youths were reexamined at each stand. Of the 301

youths, 224 were reexamined by a technician other than

the one initially measuring the youth, while the remaining 77 were reexamined by the same technician.

All together during the 4 years, 11 technicians participated in replicate measurements for this phase of the

quality control program.

Tabie I presents the percentage of total examinations performed by each technician and the percentages of intra-examiner and inter-examiner replicates

in which the 11 technicians were involved.

The table below indicates some possible sources

of bias which may affect the analysis of replicate data.

For example, assume technician number 9 was able to

replicate his own measurements very well, but his

readings were quite different from those of the other

examiners. Obviously, his results would be overrepresented in the replicate analysis because he examined

only 11.3 percent of all youths in the actual survey, but

did 16 percent of the intra-examiner replicate examinations and 13.3 percent of the inter-examiner replicate

examinations. Because of this technician’s overrepre -

sentation in the replicate study, the distribution of

intra-examiner differences would cluster closer to

zero than it really should have since this examiner

self-replicates well. On the other hand, the interexaminer distribution of differences would be considerably more skewed than it should have been since this

technician does not agree well with the other technicians’

measurements. Similar discrepancies are obvious for

other technicians. An example of an opposite effect to

that cited above is technician number 2, who did only

2.7 percent of the intra-examiner replicate measurements and 10.2 percent of the inter-examiner replicate

Table 1. Percentage of regular and replicate examinations performed by each techni.ci.an

Replicate examinations

Technician number Percentage of regular

Cycle III examinations

Percentage of intra - Percentage of f.nter -

examinations examinations

1 1.3

2 1!:: 1%;

22.8 2::; 21.4

: 6.1 4.0 2.7

c Ad.

la > G in-7 -“. . 16.7 ----

6.1 5.3

N

1%: 2::: 16.4

11.3 16.0 1:.;

2:: ::; 3:6

64
measurements, but did 13,4 percent of all examinations

in Cycle III.

Thus, the various combinations of observers for

the inter-examiner replicates and the proportions of

intra-examiner replicates were not controlled so as to

be balanced among the observers. In the survey proper

the examinations were similarly not proportionately

distributed among the observers—an imbalance caused

by the variation in the length of time the various technicians were associated with the survey,

The foregoing indicates that the distribution of

numbers of replicate examinations done by each technic ian is not the same as the distribution of the total

number of survey examination done by each in Cycle

111. This is one of the inherent problems of the present

replicate data, and limits to some extent implications

to the survey as a whole. Nevertheless, the reader

should be aware of the many problems confronting those

who conduct large-scale health surveys23 and in this

context, the present systematic approach to the collection of replicate body measurement data is adequate.

Results of

Replicate Examinations

The absolute differences between the first and the

second examinations were computed for each child on

each of the five skinfolds of interest and the results

are presented below.

Inter-Examiner Differences

There were 224 youths reexamined by a technician

other than the one who did the initial examination. The

distributions of absolute differences between the findings

of the two examinations are shown in table II.

For four of the five skinfolds the modal difference

was 0.5 mm.; for the medial calf the mode was 1.0 mm.

The largest mean differences were for the suprailiac

(2.43 mm.) and medial calf (2.41 mm.); the triceps, at

1.89 mm., was lower than these, but still higher than

the midaxillary (1.33) or subscapular (1.34) skinfolds.

The median differences for these latter two were less

than for the other three.

A widely used measure of replicability is the statistic cm, the technical error of measurement defined

n

as .?.= ~d2 . This assumes that the distribution

n

of replicate differences is normal and that the errors

of all pairs can be p@ed. The results of the calculations of this statistic are shown in table H. As expected, the largest values belong to the suprailiac and

medial calf skinfolds, the triceps displaying an intermediate value and the subscapular and midaxillary sites

the smallest.

Triceps: 1.89

Subscapular: 1.53

Midaxillary: 1.47

Suprailiac: 2.45

Medial calfi 2.44

This comparison is somewhat misleading since the

suprailiac and medial calf are the largest of the five

skinfold measurements and have the greatest variance

(see tables 1-5). On the other hand, the midaxillary

and subscapular akinfolds are highly correlated and

have similar distributions since both are trunk measurements. By expressing the technical error relative

to the appropriate mean, a coefficient of variation

(i.e., a measure of s’efotive error) is obtained. Thus,

technical error coefficient of variation = x 100

average measurement

Since,. in Cycle III, the average values for these

skinfolds over all ages and sexes were:

Triceps: 12.25

Subscapular: 9.97

Midaxillary: 8.47

Suprailiac: 13.93

Medial calfi 14.38

the following are the coefficients of variation:

Triceps: 15.44

Subscapular: 15.37

Midaxillary: 17.39

Suprailiac: 17.67

Medial calti 17.09

Viewed in terms of relative error the suprailiac

and medial calf skinfolds continue to show the poorest

replication. However, the midaxillary also falls into

this category.

lntra-Examiner Differences

A similar analysis was also conducted for the 77

youths reexamined by the same technician. The distributions of differences are shown in table 111.

Here, the triceps measurement displays the smallest mean difference and, aa before, the medial calf

and suprailiac the largest. These two also have the

largest median differences, the suprailiac being the

highest of the five. The technical error of the triceps

is the least of the five:

Triceps: 0.80

Subscapular: 1.83

Midaxillary: 2.08

Suprsiliac: 1.87

NOTE: The list of references follows the text. Medial calf: 1.44

65
Table II. Distribution of inter-examinerdifferences between the initial and the rc

. ..A. -––. .—-A. ––— e.. – -L. x.–—. .,.. . . . .. .

.acace exammauons zor me rave sm.nrows iiiiir=e~ ‘bsO1ute Difference Triceps skinfold

E

3ubscapularskinfold Midaxillary skinfoli Suprailiac skinfold Medial calf skinfold

?requency1 Percent Frequencyl I Percent Frequencyl ?ercent ?mquencyl I Percent

:: 2::;

0.0

0

1::!

X 9.4

16

22 :::

18

:::

: 4.9

4 1.8

1

2 ::;

2 0.9

2 0.9

0.9

: 0.0

0 0.0

0 0.0

0 0.0

: i:

o 0.0

1 0.5

: t!

1 0.5

0 0.0

0 0.0

0 0.0

10.4

:; lj.:

o

1!::

:(34) 14.4

10.4

16 7,2

3.6

1:

12 ;:;

3 .

: ::!

4

4 1:8

1

::;

: 0.9

0 0.0

0 0.0

: :::

0.9

: 0.0

0.5

: 0.0

1 0.5

0 :.g

1

1 0:5

0.0

:?:

-0.9

;::

2:5

3.0

t:

4.5

i:

6.0

6.5

;::

8.0

;:5

1:::

10.5

;:,g

12:0

12.5

13.0

13.5

16.0

48

61

1

4:

17

15

11

4

:

0

5

3

2

:

0

1

1

1

:

1

0

:

0

0

0

0

21.4

27.2

:.:

1;::

u

1.8

1.3

2.7

0.0

:::

0.9

0.4

$;

0.4

0.4

0.4

:::

0.4

0.0

$8

0.0

0.0

0.0

0.0

40

64

0

:;

17

9

6

3

3

1

6

1

2

0

0

1

:

0

:

1

0

0

0

0

0

0

0

17.9

28.6

0.0

1$::

1+.;

4:0

2.7

1.3

;::

::i

0.9

0.0

0.0

0.4

0.4

0.0

0.0

:::

0.4

0.0

%:

0.0

0.0

0.0

0.0

:?

o

3:

24(26)

19

12

16

1:

4

:

4

4

;

2

1

1

:

1

0

0

1

1

1

1

0

11.3

16.7

0.0

1!:!

10.8

8.6

5.4

;::

:::

;:;

1.8

1.8

i :

0.9

0.5

0.5

::;

0.5

0.0

:::

0.5

0.5

0.5

0.0

I

Sample size, n 224 100.0 \ 224 ] 100.0

Mean difference,

z, in mm.

Median in mm.

Mode in um.

Zd2

Zd2f2n

224 100.0 222 100.0

1.89

1.5

160;:2

3.58

*.;4 1.33

1.0

105!:? 97!;;

2.35 2.17

2.43

1.5

0.5

2664.8

6.00

2.41

1.5

264$ !

5.97

lNumber of replicate examinations exhibiting indicated differences.

2Such differencesmay be caused by failure of technicians to round measurement to nearest half-millimeter or by a miscoding

error undetected during imputation.

Table III. Distribution of intra-examinerdifferences between the initial and the reDlicate examinations for the five skinfolds

$yf;tc Triceps skinfold ubscapular skinfold :idsxillaryskinfold :uprailiacskinfold sdial calf skinfold

ence, d, ill IMU

1ifference

squ;~ed,

kequencyl Percent Frequenty1 Percent Frequencyl Percent Frequencyz Percent Frequenty1 Percent

0.0

0.5

1.0

1.5

2.0

:::

M

4.5

5,0

5.5

6.0

7.0

18::

19.0

23.0

27.3

35.1

16.9

9.1

5.2

N

0.0

1.3

:::

0.0

0.0

8::

0.0

0.0

0.0

100.0

37.7

28.6

14.3

;.:

:::

1.3

1.3

:::

0.0

iii

0.0

0.0

$:

100.0

31.2

31.2

18.2

5.2

6.5

1.3

M

:.:

2:6

0.0

0.0

:::

0.0

0.0

1.3

10.4

16.9

16.9

14.3

9.1

?::

2.6

6.5

0.0

5.2

1.3

1.3

i:

:::

0.0

Sample size,n

Mean difference,

a,in w

Median in um.

Mode in mm

;%/2n

77 77 77 I 100.0 77 100.0 77 100.0

0.78

0.5

9:::

0.64

1.05

0.5

51::!

3.34

1,10

0.5

66::;

4.31

1.97

1.5

52;:~

3.44

1.44

1.0

330::

2.15

1Number of replicate examinations exhibiting indicateddifferences.
Computation of coefficients of variation accentuates

the intra-examiner precision in triceps measurement.

The coefficients of variation are as follows:

Triceps: 6.51

Subscapular: 18.33

Midaxillary: 24.51

Suprailiac: 13.45

Medial calfi 10.36

The triceps measurement obviously has the lowest

coefficient of variation of the five skinfold measurements under consideration, while the midaxillary skinfold exhibits the worst replicability.

Within each skinfold, the significance of differences between the intra- and inter-observer errors of

measurement were tested by computing the F ratios

of their squares. The results were as follows:

Triceps: 4.20

Subscapular: 1.42

Midaxillary: 1.29

Suprailiac: “1.73

Medial calfi ‘2.72

Tests of these at the .01 level (to keep the overall

error rate below 5 percent) showed that the triceps,

suprailidc, and medial calf were those of the five in

which the inter- and intra-examiner technical errors

differ significantly. That is, agreement was significantly better when the same observer replicated the

initial measurement. For the other two skinfolda, the

error associated with two observers was no greater

than the intra-observer error.

These findings indicate that error in skinfold measurement is related to both the site and number of

observers utilized. The measurement of the thickness

of the triceps skinfold involves highly individual

techniques, probably related to the precise spot over

the muscle, the manner in which the fold is “picked

Up,11 and the pointat which the caliper faces make

contact with the skin. In addition, although a formally

analyzed study was not conducted, a clinical impression

was formed in the training sessions that the precise

site chosen for measurement was more critical in the

triceps region than in the others (presumably the subcutaneous fat varies in thickness more in the triceps

region as one strays from the exact site—i.e., around

the circumference of the arm —tbsn in the other regions).

A single observer will become quite consistent in terms

of his or her own technique, and self-replication will

be quite high.

Suprailiac and medial calf replication is also related to observer number. The suprailiac skinfold displays, in some cases, extremely high values in certain

individuals, and slight differences in individual techniques may cause aignificsntly poorer replicates between observers.

The medial calf skinfold is technically the most

difficult of the five to measure. In addition, as with the

suprsiliac, its values may be quitelarge.Therefore

it is subject to significant inter-observer error.

On the other hand, such individualized techniques

are not as important for the subscapular and midaxillary skinfolds since the adipose layer in these regions

is thinner and more uniform in thickness than in the

arm, The associated error is more likely to be randomized and not to be so strongly affected by “examinerspecific” factors.

Conclusions

From the above, some conclusions may be drawn

relative to the error of measurement associated with

the HES. The median error for all skinfolds is 1.0 to

1.s mm. This error, though absolutely small, is relatively quite high in view of the usual thickness of skinfolds encountered. In addition, quite large errors can

occur, replicate differences of 12.5 mm. being observed

for the triceps, 10.5 mm. for the subscapular and midsxillary folds, 13.5 for the suprailiac, and 16.0 for the

medial calf fold. These errors remain as residuals

despite the careful quality control exercised throughout Cycle III. The meaning of such errors may be

evaluated only in light of the fact that the measurement

of body fat is of considerable biomedical import and,

in many cases, skinfolds provide tbe only estimates

available.

With well-trained and supervised observers, the

residual errors of measurement are the same for the

subscapular and midsxillary skinfolds regardless of

whether one or several observers are utilized. Such is

not the case for the triceps, suprailiac, or medial calf,

however, because the residual is significantly less when

only one observer does the measuring. On the other hand,

the possibility of systematic errors is greater with

only one observer, leading to a potentially systematic

bias in the distributions.

In a longitudinal study, a single observer is always

preferable. The major purpose of such a design is to

determine change in individuals over time. A single

observer will provide more consistent readings and

therefore a more accurate estimate of change. However, since use of a single observer increases the

possibility of systematic bias, the reliability of longitudinal studies is reduced for estimates of the distribution of absolute values in the general population.

In a cross-sectional study, multiple examiners are

preferable so far as the subscapular and midaxillary

skinfolds are concerned. Not only are residual errors

of measurement the same regardless of whether one

or several observers are used, but also the systematic

bias introduced by use of a single observer will be

eliminated.

For cross-sectional studies involving the other

three skinfolds, the situation is more complex. If

67
the purpose is to estimate their distributions in a

population, multiple examiners will provide better estimates since systematic error will be more likely to

be reduced.

If the purpose is to make comparisons between

groups, then the design of the study, based on considerations of all factors, must reconcile two opposing

problems:

(1) Multiple examiners will increase the variability of

the distribution because of the inclusion of interexaminer errors of measurement.

(2) Single-examiner measurements will result in a

variance more comparable to the true value for the

population. However, since a single observer may

measure different kinds of individuals in a systematically different way, new problems of bias maybe

introduced.

—ooo —

68
Series 1.

Series 2,

Series 3.

Series 4.

Series 10.

Series 11.

Series 12.

Series 13.

Series 14.

Series 20.

Series 21.

Sevies 22.

OUTLINE OF REPORT SERIES FOR VITAL AND HEALTH STATISTICS

Originally Public Health Service Publicatwn No. 1000

Programs and collection pvocedures.— Reports which describe the general programs of the National

Center for Health Statistics and its offices and divisions, data collection methods used, definitions,

and other material necessary for understanding the data.

Data evaluation and methods research. —Studies of new statistical methodology including: experimental tests of new survey methods, studies of vital statistics collection methods, new analytical

techniques, objective evaluations of reliability of collected data, contributions to statistical theory.

Analytical studies. — Reports presenting analytical or interpretive studies based on vital and health

statistics, carrying the analysis further than the expository types of reports in the other series.

Documents and committee reports. — Final reports of major committees concerned with vital and

health statistics, and documents such as recommended model vital registration laws and revised birth

and death certificates.

Data from (he Health Interview SuYvey. —Statistics on illness, accidental injuries, disability, use of

hospital, medical, dental, and other services, and other health-related topics, based on data collected

in a continuing national household interview survey.

Data from the Health Examination Survey. —[)ata from direct examination, testing, and measurement of national samples of the population provide the basis for two types of reports: (1) estimates

of the medically defined prevalence of specific diseases in the United States and the distributions of

the population with reqpect to physical, physiological, and psychological characteristics; and (2)

:malysis of relationships among the various measurements without reference to an explicit finite

universe of persons.

Data from the Institutional Population Surveys. — Statistics relating to the health characteristics of

persons in institutions, and on medical, nursing, and personal care received, based on national

samples of establishments providing these services and samples of the residents or patients.

Data from the Hospital Discharge Survey.— Statistics relating to discharged patients in short-stay

hospitals, based on a sample of patient records in a national sample of hospitals.

Data on health resources: manpower and facilities. — Statistics on the numbers, geographic distribution, and characteristics of health resources including physicians, dentists, nurses, other health

manpower occupations, hospitals, nursimz homes, and outpatient and other inpatient facilities.

Data on mortality. —Various statistics on mortality other than as included in annual or monthly

reports —special analyses by cause of death, age, and other demographic variables, also geographic

and time series analyses.

Data on natality, marriage, and divorce. — Various statistics on natality, marriage, and divorce other

than as included in annual or monthly reports— special analyses by demographic variables, also

geographic and time series analyses, studies of fertility.

Data from the National Natality and Mortality Surveys. —Statistics on characteristics of births and

deaths not available from the vital records, based on sample surveys stemming from these records,

inducting such topics as mortality by socioeconomic CIP~s, medical experience in the last year of

life, characteristics of pregnancy. ~’tc.

For a list of titles of reports published in these series, write to: Office ui’ Information

v

National Center for Health Statistics

/ublic Health Service, HRA

Rockviile, kid, 20852

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